fe51d4cdfe
r323954 changed the mp ring behaviour when 64-bit atomics were available to abdicate the TX ring rather than having one become a consumer thereby running to completion on TX. The consumer of the mp ring was then triggered in the tx task rather than blocking the TX call. While this significantly lowered the number of RX drops in small-packet forwarding, it also negatively impacts TX performance. With this change, the default behaviour is reverted, causing one TX ring to become a consumer during the enqueue call. A new sysctl, dev.X.Y.iflib.tx_abdicate is added to control this behaviour. Reviewed by: gallatin Sponsored by: Limelight Networks Differential Revision: https://reviews.freebsd.org/D16302
72 lines
2.7 KiB
C
72 lines
2.7 KiB
C
/*-
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* Copyright (c) 2014 Chelsio Communications, Inc.
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* All rights reserved.
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* Written by: Navdeep Parhar <np@FreeBSD.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 AUTHOR 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 AUTHOR 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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* $FreeBSD$
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*
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*/
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#ifndef __NET_MP_RING_H
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#define __NET_MP_RING_H
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#ifndef _KERNEL
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#error "no user-serviceable parts inside"
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#endif
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struct ifmp_ring;
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typedef u_int (*mp_ring_drain_t)(struct ifmp_ring *, u_int, u_int);
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typedef u_int (*mp_ring_can_drain_t)(struct ifmp_ring *);
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typedef void (*mp_ring_serial_t)(struct ifmp_ring *);
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struct ifmp_ring {
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volatile uint64_t state __aligned(CACHE_LINE_SIZE);
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int size __aligned(CACHE_LINE_SIZE);
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void * cookie;
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struct malloc_type * mt;
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mp_ring_drain_t drain;
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mp_ring_can_drain_t can_drain; /* cheap, may be unreliable */
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counter_u64_t enqueues;
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counter_u64_t drops;
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counter_u64_t starts;
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counter_u64_t stalls;
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counter_u64_t restarts; /* recovered after stalling */
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counter_u64_t abdications;
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#ifdef NO_64BIT_ATOMICS
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struct mtx lock;
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#endif
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void * volatile items[] __aligned(CACHE_LINE_SIZE);
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};
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int ifmp_ring_alloc(struct ifmp_ring **, int, void *, mp_ring_drain_t,
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mp_ring_can_drain_t, struct malloc_type *, int);
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void ifmp_ring_free(struct ifmp_ring *);
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int ifmp_ring_enqueue(struct ifmp_ring *, void **, int, int, int);
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void ifmp_ring_check_drainage(struct ifmp_ring *, int);
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void ifmp_ring_reset_stats(struct ifmp_ring *);
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int ifmp_ring_is_idle(struct ifmp_ring *);
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int ifmp_ring_is_stalled(struct ifmp_ring *r);
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#endif
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