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libpthread: allocate rwlocks and spinlocks in dedicated cachelines

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Reduces severe performance degradation due to false-sharing. Note that this
does not account for hardware which can perform adjacent cacheline prefetch.

[mjg: massaged the commit message and the patch to use aligned_alloc
instead of malloc]

PR:	272238
MFC after:	1 week
This commit is contained in:
Greg Becker 2023-06-26 20:08:29 -05:00 committed by Mateusz Guzik
parent 4a402dfe0b
commit a6c0d801ca
2 changed files with 6 additions and 2 deletions
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3
lib/libthr/thread/thr_pspinlock.c
View File

@ -60,7 +60,8 @@ _pthread_spin_init(pthread_spinlock_t *lock, int pshared)
if (lock == NULL)
return (EINVAL);
if (pshared == PTHREAD_PROCESS_PRIVATE) {
lck = malloc(sizeof(struct pthread_spinlock));
lck = aligned_alloc(CACHE_LINE_SIZE,
roundup(sizeof(struct pthread_spinlock), CACHE_LINE_SIZE));
if (lck == NULL)
return (ENOMEM);
*lock = lck;

5
lib/libthr/thread/thr_rwlock.c
View File

@ -32,6 +32,7 @@ __FBSDID("$FreeBSD$");
#include <errno.h>
#include <limits.h>
#include <stdlib.h>
#include <string.h>
#include "namespace.h"
#include <pthread.h>
@ -102,9 +103,11 @@ rwlock_init(pthread_rwlock_t *rwlock, const pthread_rwlockattr_t *attr)
if (attr == NULL || *attr == NULL ||
(*attr)->pshared == PTHREAD_PROCESS_PRIVATE) {
prwlock = calloc(1, sizeof(struct pthread_rwlock));
prwlock = aligned_alloc(CACHE_LINE_SIZE,
roundup(sizeof(struct pthread_rwlock), CACHE_LINE_SIZE));
if (prwlock == NULL)
return (ENOMEM);
memset(prwlock, 0, sizeof(struct pthread_rwlock));
*rwlock = prwlock;
} else {
prwlock = __thr_pshared_offpage(rwlock, 1);