bc2389b828
Although an `isc_histo_t` is thread-safe, it can suffer from cache contention under heavy load. To avoid this, an `isc_histomulti_t` contains a histogram per thread, so updates are local and low-contention.
66 lines
1.2 KiB
C
66 lines
1.2 KiB
C
/*
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* Copyright (C) Internet Systems Consortium, Inc. ("ISC")
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*
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* SPDX-License-Identifier: MPL-2.0
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*
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* This Source Code Form is subject to the terms of the Mozilla Public
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* License, v. 2.0. If a copy of the MPL was not distributed with this
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* file, you can obtain one at https://mozilla.org/MPL/2.0/.
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*
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* See the COPYRIGHT file distributed with this work for additional
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* information regarding copyright ownership.
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*/
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#include <stdlib.h>
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#include <sys/types.h>
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#include <unistd.h>
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#include <isc/lang.h>
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#include <isc/thread.h>
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#include <isc/tid.h>
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#include <isc/util.h>
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/**
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* Private
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*/
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#define ISC_TID_UNKNOWN UINT32_MAX
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static thread_local uint32_t tid_local = ISC_TID_UNKNOWN;
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/*
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* Zero is a better nonsense value in this case than ISC_TID_UNKNOWN;
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* avoids things like trying to allocate 32GB of per-thread counters.
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*/
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static uint32_t tid_count = 0;
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/**
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* Protected
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*/
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void
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isc__tid_init(uint32_t tid) {
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REQUIRE(tid_local == ISC_TID_UNKNOWN || tid_local == tid);
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tid_local = tid;
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}
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void
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isc__tid_initcount(uint32_t count) {
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REQUIRE(tid_count == 0 || tid_count == count);
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tid_count = count;
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}
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/**
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* Public
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*/
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uint32_t
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isc_tid(void) {
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return (tid_local);
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}
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uint32_t
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isc_tid_count(void) {
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return (tid_count);
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}
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