9cf64d6c35
Introduce counter(9) API, that implements fast and raceless counters, provided (but not limited to) for gathering of statistical data. See http://lists.freebsd.org/pipermail/freebsd-arch/2013-April/014204.html for more details. In collaboration with: kib Reviewed by: luigi Tested by: ae, ray Sponsored by: Nginx, Inc.
110 lines
2.7 KiB
C
110 lines
2.7 KiB
C
/*-
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* Copyright (c) 2012 Gleb Smirnoff <glebius@FreeBSD.org>
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* All rights reserved.
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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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#include <sys/cdefs.h>
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__FBSDID("$FreeBSD$");
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#include <sys/param.h>
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#include <sys/systm.h>
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#include <sys/counter.h>
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#include <sys/kernel.h>
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#include <sys/smp.h>
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#include <sys/sysctl.h>
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#include <vm/uma.h>
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static uma_zone_t uint64_pcpu_zone;
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void
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counter_u64_zero(counter_u64_t c)
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{
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int i;
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for (i = 0; i < mp_ncpus; i++)
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*(uint64_t *)((char *)c + sizeof(struct pcpu) * i) = 0;
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}
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uint64_t
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counter_u64_fetch(counter_u64_t c)
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{
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uint64_t r;
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int i;
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r = 0;
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for (i = 0; i < mp_ncpus; i++)
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r += *(uint64_t *)((char *)c + sizeof(struct pcpu) * i);
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return (r);
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}
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counter_u64_t
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counter_u64_alloc(int flags)
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{
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counter_u64_t r;
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r = uma_zalloc(uint64_pcpu_zone, flags);
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if (r != NULL)
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counter_u64_zero(r);
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return (r);
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}
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void
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counter_u64_free(counter_u64_t c)
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{
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uma_zfree(uint64_pcpu_zone, c);
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}
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int
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sysctl_handle_counter_u64(SYSCTL_HANDLER_ARGS)
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{
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uint64_t out;
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int error;
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out = counter_u64_fetch(*(counter_u64_t *)arg1);
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error = SYSCTL_OUT(req, &out, sizeof(uint64_t));
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if (error || !req->newptr)
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return (error);
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/*
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* Any write attempt to a counter zeroes it.
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*/
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counter_u64_zero(*(counter_u64_t *)arg1);
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return (0);
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}
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static void
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counter_startup(void)
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{
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uint64_pcpu_zone = uma_zcreate("uint64 pcpu", sizeof(uint64_t),
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NULL, NULL, NULL, NULL, UMA_ALIGN_PTR, UMA_ZONE_PCPU);
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}
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SYSINIT(counter, SI_SUB_KMEM, SI_ORDER_ANY, counter_startup, NULL);
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