freebsd-dev/sys/geom/geom_kern.c
Alexander Motin 5c32e9fcb2 Optimize kern.geom.conf* sysctls.
On large systems those sysctls may generate megabytes of output.  Before
this change sbuf(9) code was resizing buffer by 4KB each time many times,
generating tons of TLB shootdowns.  Unfortunately in this case existing
sbuf_new_for_sysctl() mechanism, supposed to help with this issue, is not
applicable, since all the sbuf writes are done in different kernel thread.

This change improves situation in two ways:
 - on first sysctl call, not providing any output buffer, it sets special
sbuf drain function, just counting the data and so not needing big buffer;
 - on second sysctl call it uses as initial buffer size value saved on
previous call, so that in most cases there will be no reallocation, unless
GEOM topology changed significantly.

MFC after:	1 week
Sponsored by:	iXsystems, Inc.
2019-06-18 21:05:10 +00:00

241 lines
7.0 KiB
C

/*-
* SPDX-License-Identifier: BSD-3-Clause
*
* Copyright (c) 2002 Poul-Henning Kamp
* Copyright (c) 2002 Networks Associates Technology, Inc.
* All rights reserved.
*
* This software was developed for the FreeBSD Project by Poul-Henning Kamp
* and NAI Labs, the Security Research Division of Network Associates, Inc.
* under DARPA/SPAWAR contract N66001-01-C-8035 ("CBOSS"), as part of the
* DARPA CHATS research program.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* 2. Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the distribution.
* 3. The names of the authors may not be used to endorse or promote
* products derived from this software without specific prior written
* permission.
*
* THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
* ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
* SUCH DAMAGE.
*/
#include <sys/cdefs.h>
__FBSDID("$FreeBSD$");
#include <sys/param.h>
#include <sys/systm.h>
#include <sys/kernel.h>
#include <sys/eventhandler.h>
#include <sys/malloc.h>
#include <sys/bio.h>
#include <sys/sysctl.h>
#include <sys/proc.h>
#include <sys/unistd.h>
#include <sys/kthread.h>
#include <sys/lock.h>
#include <sys/mutex.h>
#include <sys/sbuf.h>
#include <sys/sched.h>
#include <sys/sx.h>
#include <geom/geom.h>
#include <geom/geom_int.h>
MALLOC_DEFINE(M_GEOM, "GEOM", "Geom data structures");
struct sx topology_lock;
static struct proc *g_proc;
static struct thread *g_up_td;
static struct thread *g_down_td;
static struct thread *g_event_td;
int g_debugflags;
int g_collectstats = 1;
int g_shutdown;
int g_notaste;
/*
* G_UP and G_DOWN are the two threads which push I/O through the
* stack.
*
* Things are procesed in a FIFO order, but these threads could be
* part of I/O prioritization by deciding which bios/bioqs to service
* in what order.
*
* We have only one thread in each direction, it is believed that until
* a very non-trivial workload in the UP/DOWN path this will be enough,
* but more than one can actually be run without problems.
*
* Holding the "mymutex" is a debugging feature: It prevents people
* from sleeping in the UP/DOWN I/O path by mistake or design (doing
* so almost invariably result in deadlocks since it stalls all I/O
* processing in the given direction.
*/
static void
g_up_procbody(void *arg)
{
thread_lock(g_up_td);
sched_prio(g_up_td, PRIBIO);
thread_unlock(g_up_td);
for(;;) {
g_io_schedule_up(g_up_td);
}
}
static void
g_down_procbody(void *arg)
{
thread_lock(g_down_td);
sched_prio(g_down_td, PRIBIO);
thread_unlock(g_down_td);
for(;;) {
g_io_schedule_down(g_down_td);
}
}
static void
g_event_procbody(void *arg)
{
thread_lock(g_event_td);
sched_prio(g_event_td, PRIBIO);
thread_unlock(g_event_td);
g_run_events();
/* NOTREACHED */
}
int
g_is_geom_thread(struct thread *td)
{
return (td == g_up_td || td == g_down_td || td == g_event_td);
}
static void
geom_shutdown(void *foo __unused)
{
g_shutdown = 1;
}
void
g_init(void)
{
g_trace(G_T_TOPOLOGY, "g_ignition");
sx_init(&topology_lock, "GEOM topology");
g_io_init();
g_event_init();
g_ctl_init();
kproc_kthread_add(g_event_procbody, NULL, &g_proc, &g_event_td,
RFHIGHPID, 0, "geom", "g_event");
kproc_kthread_add(g_up_procbody, NULL, &g_proc, &g_up_td,
RFHIGHPID, 0, "geom", "g_up");
kproc_kthread_add(g_down_procbody, NULL, &g_proc, &g_down_td,
RFHIGHPID, 0, "geom", "g_down");
EVENTHANDLER_REGISTER(shutdown_pre_sync, geom_shutdown, NULL,
SHUTDOWN_PRI_FIRST);
}
static int
sysctl_kern_geom_confany(struct sysctl_req *req, g_event_t *func, size_t *hint)
{
size_t len = 0;
int error = 0;
struct sbuf *sb;
if (req->oldptr == NULL) {
sb = sbuf_new(NULL, NULL, PAGE_SIZE, SBUF_FIXEDLEN |
SBUF_INCLUDENUL);
sbuf_set_drain(sb, sbuf_count_drain, &len);
g_waitfor_event(func, sb, M_WAITOK, NULL);
req->oldidx = *hint = len;
} else {
sb = sbuf_new(NULL, NULL, *hint, SBUF_AUTOEXTEND |
SBUF_INCLUDENUL);
g_waitfor_event(func, sb, M_WAITOK, NULL);
*hint = sbuf_len(sb);
error = SYSCTL_OUT(req, sbuf_data(sb), sbuf_len(sb));
}
sbuf_delete(sb);
return error;
}
static int
sysctl_kern_geom_conftxt(SYSCTL_HANDLER_ARGS)
{
static size_t hint = PAGE_SIZE;
return (sysctl_kern_geom_confany(req, g_conftxt, &hint));
}
static int
sysctl_kern_geom_confdot(SYSCTL_HANDLER_ARGS)
{
static size_t hint = PAGE_SIZE;
return (sysctl_kern_geom_confany(req, g_confdot, &hint));
}
static int
sysctl_kern_geom_confxml(SYSCTL_HANDLER_ARGS)
{
static size_t hint = PAGE_SIZE;
return (sysctl_kern_geom_confany(req, g_confxml, &hint));
}
SYSCTL_NODE(_kern, OID_AUTO, geom, CTLFLAG_RW, 0, "GEOMetry management");
SYSCTL_PROC(_kern_geom, OID_AUTO, confxml, CTLTYPE_STRING|CTLFLAG_RD,
0, 0, sysctl_kern_geom_confxml, "",
"Dump the GEOM config in XML");
SYSCTL_PROC(_kern_geom, OID_AUTO, confdot, CTLTYPE_STRING|CTLFLAG_RD,
0, 0, sysctl_kern_geom_confdot, "",
"Dump the GEOM config in dot");
SYSCTL_PROC(_kern_geom, OID_AUTO, conftxt, CTLTYPE_STRING|CTLFLAG_RD,
0, 0, sysctl_kern_geom_conftxt, "",
"Dump the GEOM config in txt");
SYSCTL_INT(_kern_geom, OID_AUTO, debugflags, CTLFLAG_RWTUN,
&g_debugflags, 0, "Set various trace levels for GEOM debugging");
SYSCTL_INT(_kern_geom, OID_AUTO, notaste, CTLFLAG_RW,
&g_notaste, 0, "Prevent GEOM tasting");
SYSCTL_INT(_kern_geom, OID_AUTO, collectstats, CTLFLAG_RW,
&g_collectstats, 0,
"Control statistics collection on GEOM providers and consumers");
SYSCTL_INT(_debug_sizeof, OID_AUTO, g_class, CTLFLAG_RD,
SYSCTL_NULL_INT_PTR, sizeof(struct g_class), "sizeof(struct g_class)");
SYSCTL_INT(_debug_sizeof, OID_AUTO, g_geom, CTLFLAG_RD,
SYSCTL_NULL_INT_PTR, sizeof(struct g_geom), "sizeof(struct g_geom)");
SYSCTL_INT(_debug_sizeof, OID_AUTO, g_provider, CTLFLAG_RD,
SYSCTL_NULL_INT_PTR, sizeof(struct g_provider), "sizeof(struct g_provider)");
SYSCTL_INT(_debug_sizeof, OID_AUTO, g_consumer, CTLFLAG_RD,
SYSCTL_NULL_INT_PTR, sizeof(struct g_consumer), "sizeof(struct g_consumer)");
SYSCTL_INT(_debug_sizeof, OID_AUTO, g_bioq, CTLFLAG_RD,
SYSCTL_NULL_INT_PTR, sizeof(struct g_bioq), "sizeof(struct g_bioq)");