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8dc10be885
mutex profiling code. As with existing mutex profiling, measurement
is done with respect to mtx_lock() instances in the code, as opposed
to specific mutexes. In particular, measure two things:
(1) Lock contention. How often did this mtx_lock() call get made and
have to sleep (or almost sleep) waiting for the lock. This helps
identify the "victims" of contention.
(2) Hold contention. How often, while the lock was held by a thread
as a result of this mtx_lock(), did another thread try to acquire
the same mutex. This helps identify the causes of contention.
I'm currently exploring adding measurement of "time waited for the
lock", but the current implementation has proven useful to me so far
so I figured I'd commit it so others could try it out. Note that this
increases the size of mutexes when MUTEX_PROFILING is enabled, so you
might find you need to further bump UMA_BOOT_PAGES. Fixes welcome.
The once over: des, others
63 lines
2.3 KiB
C
63 lines
2.3 KiB
C
/*-
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* Copyright (c) 1997 Berkeley Software Design, Inc. 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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* 3. Berkeley Software Design Inc's name may not be used to endorse or
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* promote products derived from this software without specific prior
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* written permission.
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*
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* THIS SOFTWARE IS PROVIDED BY BERKELEY SOFTWARE DESIGN INC ``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 BERKELEY SOFTWARE DESIGN INC 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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#ifndef _SYS__MUTEX_H_
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#define _SYS__MUTEX_H_
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/*
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* Sleep/spin mutex.
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*/
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struct mtx {
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struct lock_object mtx_object; /* Common lock properties. */
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volatile uintptr_t mtx_lock; /* Owner and flags. */
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volatile u_int mtx_recurse; /* Number of recursive holds. */
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#ifdef MUTEX_PROFILING
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/*
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* This does not result in variant structure sizes because
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* MUTEX_PROFILING is in opt_global.h
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*/
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u_int64_t mtx_acqtime;
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const char *mtx_filename;
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int mtx_lineno;
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/*
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* Fields relating to measuring contention on mutexes.
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* holding must be accessed atomically since it's
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* modified by threads that don't yet hold the mutex.
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* locking is only modified and referenced while
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* the mutex is held.
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*/
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u_int mtx_contest_holding;
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u_int mtx_contest_locking;
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#endif
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};
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#endif /* !_SYS__MUTEX_H_ */
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