9e59bf1911
Change 221669 by bz@bz_zenith on 2013/02/01 12:26:04 Run the initialization for polling earlier along with INTRs so that we can put network interface into polling mode by default if DEVICE_POLLING is compiled in and no interrupts are available. MFC after: 3 days Sponsored by: DARPA/AFRL
568 lines
16 KiB
C
568 lines
16 KiB
C
/*-
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* Copyright (c) 2001-2002 Luigi Rizzo
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*
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* Supported by: the Xorp Project (www.xorp.org)
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*
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* Redistribution and use in source and binary forms, with or without
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* modification, are permitted provided that the following conditions
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* are met:
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* 1. Redistributions of source code must retain the above copyright
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* notice, this list of conditions and the following disclaimer.
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* 2. Redistributions in binary form must reproduce the above copyright
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* notice, this list of conditions and the following disclaimer in the
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* documentation and/or other materials provided with the distribution.
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*
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* THIS SOFTWARE IS PROVIDED BY THE AUTHORS AND CONTRIBUTORS ``AS IS'' AND
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* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
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* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
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* ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHORS OR CONTRIBUTORS BE LIABLE
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* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
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* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
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* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
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* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
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* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
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* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
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* SUCH DAMAGE.
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*/
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#include <sys/cdefs.h>
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__FBSDID("$FreeBSD$");
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#include "opt_device_polling.h"
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#include <sys/param.h>
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#include <sys/systm.h>
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#include <sys/kernel.h>
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#include <sys/kthread.h>
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#include <sys/proc.h>
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#include <sys/eventhandler.h>
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#include <sys/resourcevar.h>
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#include <sys/socket.h> /* needed by net/if.h */
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#include <sys/sockio.h>
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#include <sys/sysctl.h>
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#include <sys/syslog.h>
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#include <net/if.h> /* for IFF_* flags */
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#include <net/netisr.h> /* for NETISR_POLL */
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#include <net/vnet.h>
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void hardclock_device_poll(void); /* hook from hardclock */
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static struct mtx poll_mtx;
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/*
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* Polling support for [network] device drivers.
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*
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* Drivers which support this feature can register with the
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* polling code.
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*
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* If registration is successful, the driver must disable interrupts,
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* and further I/O is performed through the handler, which is invoked
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* (at least once per clock tick) with 3 arguments: the "arg" passed at
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* register time (a struct ifnet pointer), a command, and a "count" limit.
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*
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* The command can be one of the following:
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* POLL_ONLY: quick move of "count" packets from input/output queues.
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* POLL_AND_CHECK_STATUS: as above, plus check status registers or do
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* other more expensive operations. This command is issued periodically
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* but less frequently than POLL_ONLY.
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*
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* The count limit specifies how much work the handler can do during the
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* call -- typically this is the number of packets to be received, or
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* transmitted, etc. (drivers are free to interpret this number, as long
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* as the max time spent in the function grows roughly linearly with the
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* count).
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*
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* Polling is enabled and disabled via setting IFCAP_POLLING flag on
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* the interface. The driver ioctl handler should register interface
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* with polling and disable interrupts, if registration was successful.
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*
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* A second variable controls the sharing of CPU between polling/kernel
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* network processing, and other activities (typically userlevel tasks):
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* kern.polling.user_frac (between 0 and 100, default 50) sets the share
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* of CPU allocated to user tasks. CPU is allocated proportionally to the
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* shares, by dynamically adjusting the "count" (poll_burst).
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*
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* Other parameters can should be left to their default values.
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* The following constraints hold
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*
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* 1 <= poll_each_burst <= poll_burst <= poll_burst_max
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* MIN_POLL_BURST_MAX <= poll_burst_max <= MAX_POLL_BURST_MAX
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*/
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#define MIN_POLL_BURST_MAX 10
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#define MAX_POLL_BURST_MAX 20000
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static uint32_t poll_burst = 5;
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static uint32_t poll_burst_max = 150; /* good for 100Mbit net and HZ=1000 */
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static uint32_t poll_each_burst = 5;
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static SYSCTL_NODE(_kern, OID_AUTO, polling, CTLFLAG_RW, 0,
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"Device polling parameters");
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SYSCTL_UINT(_kern_polling, OID_AUTO, burst, CTLFLAG_RD,
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&poll_burst, 0, "Current polling burst size");
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static int netisr_poll_scheduled;
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static int netisr_pollmore_scheduled;
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static int poll_shutting_down;
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static int poll_burst_max_sysctl(SYSCTL_HANDLER_ARGS)
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{
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uint32_t val = poll_burst_max;
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int error;
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error = sysctl_handle_int(oidp, &val, 0, req);
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if (error || !req->newptr )
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return (error);
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if (val < MIN_POLL_BURST_MAX || val > MAX_POLL_BURST_MAX)
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return (EINVAL);
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mtx_lock(&poll_mtx);
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poll_burst_max = val;
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if (poll_burst > poll_burst_max)
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poll_burst = poll_burst_max;
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if (poll_each_burst > poll_burst_max)
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poll_each_burst = MIN_POLL_BURST_MAX;
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mtx_unlock(&poll_mtx);
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return (0);
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}
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SYSCTL_PROC(_kern_polling, OID_AUTO, burst_max, CTLTYPE_UINT | CTLFLAG_RW,
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0, sizeof(uint32_t), poll_burst_max_sysctl, "I", "Max Polling burst size");
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static int poll_each_burst_sysctl(SYSCTL_HANDLER_ARGS)
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{
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uint32_t val = poll_each_burst;
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int error;
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error = sysctl_handle_int(oidp, &val, 0, req);
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if (error || !req->newptr )
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return (error);
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if (val < 1)
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return (EINVAL);
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mtx_lock(&poll_mtx);
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if (val > poll_burst_max) {
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mtx_unlock(&poll_mtx);
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return (EINVAL);
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}
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poll_each_burst = val;
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mtx_unlock(&poll_mtx);
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return (0);
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}
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SYSCTL_PROC(_kern_polling, OID_AUTO, each_burst, CTLTYPE_UINT | CTLFLAG_RW,
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0, sizeof(uint32_t), poll_each_burst_sysctl, "I",
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"Max size of each burst");
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static uint32_t poll_in_idle_loop=0; /* do we poll in idle loop ? */
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SYSCTL_UINT(_kern_polling, OID_AUTO, idle_poll, CTLFLAG_RW,
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&poll_in_idle_loop, 0, "Enable device polling in idle loop");
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static uint32_t user_frac = 50;
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static int user_frac_sysctl(SYSCTL_HANDLER_ARGS)
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{
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uint32_t val = user_frac;
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int error;
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error = sysctl_handle_int(oidp, &val, 0, req);
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if (error || !req->newptr )
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return (error);
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if (val > 99)
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return (EINVAL);
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mtx_lock(&poll_mtx);
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user_frac = val;
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mtx_unlock(&poll_mtx);
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return (0);
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}
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SYSCTL_PROC(_kern_polling, OID_AUTO, user_frac, CTLTYPE_UINT | CTLFLAG_RW,
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0, sizeof(uint32_t), user_frac_sysctl, "I",
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"Desired user fraction of cpu time");
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static uint32_t reg_frac_count = 0;
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static uint32_t reg_frac = 20 ;
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static int reg_frac_sysctl(SYSCTL_HANDLER_ARGS)
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{
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uint32_t val = reg_frac;
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int error;
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error = sysctl_handle_int(oidp, &val, 0, req);
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if (error || !req->newptr )
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return (error);
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if (val < 1 || val > hz)
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return (EINVAL);
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mtx_lock(&poll_mtx);
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reg_frac = val;
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if (reg_frac_count >= reg_frac)
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reg_frac_count = 0;
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mtx_unlock(&poll_mtx);
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return (0);
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}
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SYSCTL_PROC(_kern_polling, OID_AUTO, reg_frac, CTLTYPE_UINT | CTLFLAG_RW,
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0, sizeof(uint32_t), reg_frac_sysctl, "I",
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"Every this many cycles check registers");
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static uint32_t short_ticks;
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SYSCTL_UINT(_kern_polling, OID_AUTO, short_ticks, CTLFLAG_RD,
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&short_ticks, 0, "Hardclock ticks shorter than they should be");
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static uint32_t lost_polls;
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SYSCTL_UINT(_kern_polling, OID_AUTO, lost_polls, CTLFLAG_RD,
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&lost_polls, 0, "How many times we would have lost a poll tick");
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static uint32_t pending_polls;
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SYSCTL_UINT(_kern_polling, OID_AUTO, pending_polls, CTLFLAG_RD,
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&pending_polls, 0, "Do we need to poll again");
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static int residual_burst = 0;
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SYSCTL_INT(_kern_polling, OID_AUTO, residual_burst, CTLFLAG_RD,
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&residual_burst, 0, "# of residual cycles in burst");
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static uint32_t poll_handlers; /* next free entry in pr[]. */
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SYSCTL_UINT(_kern_polling, OID_AUTO, handlers, CTLFLAG_RD,
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&poll_handlers, 0, "Number of registered poll handlers");
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static uint32_t phase;
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SYSCTL_UINT(_kern_polling, OID_AUTO, phase, CTLFLAG_RD,
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&phase, 0, "Polling phase");
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static uint32_t suspect;
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SYSCTL_UINT(_kern_polling, OID_AUTO, suspect, CTLFLAG_RD,
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&suspect, 0, "suspect event");
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static uint32_t stalled;
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SYSCTL_UINT(_kern_polling, OID_AUTO, stalled, CTLFLAG_RD,
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&stalled, 0, "potential stalls");
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static uint32_t idlepoll_sleeping; /* idlepoll is sleeping */
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SYSCTL_UINT(_kern_polling, OID_AUTO, idlepoll_sleeping, CTLFLAG_RD,
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&idlepoll_sleeping, 0, "idlepoll is sleeping");
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#define POLL_LIST_LEN 128
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struct pollrec {
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poll_handler_t *handler;
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struct ifnet *ifp;
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};
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static struct pollrec pr[POLL_LIST_LEN];
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static void
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poll_shutdown(void *arg, int howto)
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{
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poll_shutting_down = 1;
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}
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static void
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init_device_poll(void)
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{
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mtx_init(&poll_mtx, "polling", NULL, MTX_DEF);
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EVENTHANDLER_REGISTER(shutdown_post_sync, poll_shutdown, NULL,
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SHUTDOWN_PRI_LAST);
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}
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SYSINIT(device_poll, SI_SUB_SOFTINTR, SI_ORDER_MIDDLE, init_device_poll, NULL);
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/*
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* Hook from hardclock. Tries to schedule a netisr, but keeps track
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* of lost ticks due to the previous handler taking too long.
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* Normally, this should not happen, because polling handler should
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* run for a short time. However, in some cases (e.g. when there are
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* changes in link status etc.) the drivers take a very long time
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* (even in the order of milliseconds) to reset and reconfigure the
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* device, causing apparent lost polls.
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*
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* The first part of the code is just for debugging purposes, and tries
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* to count how often hardclock ticks are shorter than they should,
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* meaning either stray interrupts or delayed events.
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*/
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void
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hardclock_device_poll(void)
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{
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static struct timeval prev_t, t;
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int delta;
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if (poll_handlers == 0 || poll_shutting_down)
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return;
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microuptime(&t);
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delta = (t.tv_usec - prev_t.tv_usec) +
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(t.tv_sec - prev_t.tv_sec)*1000000;
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if (delta * hz < 500000)
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short_ticks++;
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else
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prev_t = t;
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if (pending_polls > 100) {
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/*
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* Too much, assume it has stalled (not always true
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* see comment above).
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*/
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stalled++;
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pending_polls = 0;
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phase = 0;
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}
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if (phase <= 2) {
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if (phase != 0)
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suspect++;
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phase = 1;
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netisr_poll_scheduled = 1;
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netisr_pollmore_scheduled = 1;
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netisr_sched_poll();
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phase = 2;
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}
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if (pending_polls++ > 0)
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lost_polls++;
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}
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/*
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* ether_poll is called from the idle loop.
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*/
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static void
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ether_poll(int count)
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{
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int i;
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mtx_lock(&poll_mtx);
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if (count > poll_each_burst)
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count = poll_each_burst;
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for (i = 0 ; i < poll_handlers ; i++)
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pr[i].handler(pr[i].ifp, POLL_ONLY, count);
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mtx_unlock(&poll_mtx);
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}
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/*
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* netisr_pollmore is called after other netisr's, possibly scheduling
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* another NETISR_POLL call, or adapting the burst size for the next cycle.
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*
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* It is very bad to fetch large bursts of packets from a single card at once,
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* because the burst could take a long time to be completely processed, or
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* could saturate the intermediate queue (ipintrq or similar) leading to
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* losses or unfairness. To reduce the problem, and also to account better for
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* time spent in network-related processing, we split the burst in smaller
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* chunks of fixed size, giving control to the other netisr's between chunks.
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* This helps in improving the fairness, reducing livelock (because we
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* emulate more closely the "process to completion" that we have with
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* fastforwarding) and accounting for the work performed in low level
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* handling and forwarding.
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*/
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static struct timeval poll_start_t;
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void
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netisr_pollmore()
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{
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struct timeval t;
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int kern_load;
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mtx_lock(&poll_mtx);
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if (!netisr_pollmore_scheduled) {
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mtx_unlock(&poll_mtx);
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return;
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}
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netisr_pollmore_scheduled = 0;
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phase = 5;
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if (residual_burst > 0) {
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netisr_poll_scheduled = 1;
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netisr_pollmore_scheduled = 1;
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netisr_sched_poll();
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mtx_unlock(&poll_mtx);
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/* will run immediately on return, followed by netisrs */
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return;
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}
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/* here we can account time spent in netisr's in this tick */
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microuptime(&t);
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kern_load = (t.tv_usec - poll_start_t.tv_usec) +
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(t.tv_sec - poll_start_t.tv_sec)*1000000; /* us */
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kern_load = (kern_load * hz) / 10000; /* 0..100 */
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if (kern_load > (100 - user_frac)) { /* try decrease ticks */
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if (poll_burst > 1)
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poll_burst--;
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} else {
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if (poll_burst < poll_burst_max)
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poll_burst++;
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}
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pending_polls--;
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if (pending_polls == 0) /* we are done */
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phase = 0;
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else {
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/*
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* Last cycle was long and caused us to miss one or more
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* hardclock ticks. Restart processing again, but slightly
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* reduce the burst size to prevent that this happens again.
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*/
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poll_burst -= (poll_burst / 8);
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if (poll_burst < 1)
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poll_burst = 1;
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netisr_poll_scheduled = 1;
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netisr_pollmore_scheduled = 1;
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netisr_sched_poll();
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phase = 6;
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}
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mtx_unlock(&poll_mtx);
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}
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/*
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* netisr_poll is typically scheduled once per tick.
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*/
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void
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netisr_poll(void)
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{
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int i, cycles;
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enum poll_cmd arg = POLL_ONLY;
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mtx_lock(&poll_mtx);
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if (!netisr_poll_scheduled) {
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mtx_unlock(&poll_mtx);
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return;
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}
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netisr_poll_scheduled = 0;
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phase = 3;
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if (residual_burst == 0) { /* first call in this tick */
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microuptime(&poll_start_t);
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if (++reg_frac_count == reg_frac) {
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arg = POLL_AND_CHECK_STATUS;
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reg_frac_count = 0;
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}
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residual_burst = poll_burst;
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}
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cycles = (residual_burst < poll_each_burst) ?
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residual_burst : poll_each_burst;
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residual_burst -= cycles;
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for (i = 0 ; i < poll_handlers ; i++)
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pr[i].handler(pr[i].ifp, arg, cycles);
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phase = 4;
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mtx_unlock(&poll_mtx);
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}
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/*
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* Try to register routine for polling. Returns 0 if successful
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* (and polling should be enabled), error code otherwise.
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* A device is not supposed to register itself multiple times.
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*
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* This is called from within the *_ioctl() functions.
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*/
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int
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ether_poll_register(poll_handler_t *h, struct ifnet *ifp)
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{
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int i;
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KASSERT(h != NULL, ("%s: handler is NULL", __func__));
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KASSERT(ifp != NULL, ("%s: ifp is NULL", __func__));
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mtx_lock(&poll_mtx);
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if (poll_handlers >= POLL_LIST_LEN) {
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/*
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* List full, cannot register more entries.
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* This should never happen; if it does, it is probably a
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* broken driver trying to register multiple times. Checking
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* this at runtime is expensive, and won't solve the problem
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* anyways, so just report a few times and then give up.
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*/
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static int verbose = 10 ;
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if (verbose >0) {
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log(LOG_ERR, "poll handlers list full, "
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"maybe a broken driver ?\n");
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verbose--;
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}
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mtx_unlock(&poll_mtx);
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return (ENOMEM); /* no polling for you */
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}
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for (i = 0 ; i < poll_handlers ; i++)
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if (pr[i].ifp == ifp && pr[i].handler != NULL) {
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mtx_unlock(&poll_mtx);
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log(LOG_DEBUG, "ether_poll_register: %s: handler"
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" already registered\n", ifp->if_xname);
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return (EEXIST);
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}
|
|
|
|
pr[poll_handlers].handler = h;
|
|
pr[poll_handlers].ifp = ifp;
|
|
poll_handlers++;
|
|
mtx_unlock(&poll_mtx);
|
|
if (idlepoll_sleeping)
|
|
wakeup(&idlepoll_sleeping);
|
|
return (0);
|
|
}
|
|
|
|
/*
|
|
* Remove interface from the polling list. Called from *_ioctl(), too.
|
|
*/
|
|
int
|
|
ether_poll_deregister(struct ifnet *ifp)
|
|
{
|
|
int i;
|
|
|
|
KASSERT(ifp != NULL, ("%s: ifp is NULL", __func__));
|
|
|
|
mtx_lock(&poll_mtx);
|
|
|
|
for (i = 0 ; i < poll_handlers ; i++)
|
|
if (pr[i].ifp == ifp) /* found it */
|
|
break;
|
|
if (i == poll_handlers) {
|
|
log(LOG_DEBUG, "ether_poll_deregister: %s: not found!\n",
|
|
ifp->if_xname);
|
|
mtx_unlock(&poll_mtx);
|
|
return (ENOENT);
|
|
}
|
|
poll_handlers--;
|
|
if (i < poll_handlers) { /* Last entry replaces this one. */
|
|
pr[i].handler = pr[poll_handlers].handler;
|
|
pr[i].ifp = pr[poll_handlers].ifp;
|
|
}
|
|
mtx_unlock(&poll_mtx);
|
|
return (0);
|
|
}
|
|
|
|
static void
|
|
poll_idle(void)
|
|
{
|
|
struct thread *td = curthread;
|
|
struct rtprio rtp;
|
|
|
|
rtp.prio = RTP_PRIO_MAX; /* lowest priority */
|
|
rtp.type = RTP_PRIO_IDLE;
|
|
PROC_SLOCK(td->td_proc);
|
|
rtp_to_pri(&rtp, td);
|
|
PROC_SUNLOCK(td->td_proc);
|
|
|
|
for (;;) {
|
|
if (poll_in_idle_loop && poll_handlers > 0) {
|
|
idlepoll_sleeping = 0;
|
|
ether_poll(poll_each_burst);
|
|
thread_lock(td);
|
|
mi_switch(SW_VOL, NULL);
|
|
thread_unlock(td);
|
|
} else {
|
|
idlepoll_sleeping = 1;
|
|
tsleep(&idlepoll_sleeping, 0, "pollid", hz * 3);
|
|
}
|
|
}
|
|
}
|
|
|
|
static struct proc *idlepoll;
|
|
static struct kproc_desc idlepoll_kp = {
|
|
"idlepoll",
|
|
poll_idle,
|
|
&idlepoll
|
|
};
|
|
SYSINIT(idlepoll, SI_SUB_KTHREAD_VM, SI_ORDER_ANY, kproc_start,
|
|
&idlepoll_kp);
|