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[pkgsrc/trunk]: pkgsrc/x11/libxshmfence libxshmfence: improve performance of ...
details: https://anonhg.NetBSD.org/pkgsrc/rev/b9732f0e4152
branches: trunk
changeset: 411944:b9732f0e4152
user: tnn <tnn%pkgsrc.org@localhost>
date: Sun Feb 23 22:47:47 2020 +0000
description:
libxshmfence: improve performance of semaphore backend. Bump rev.
It used more locking that necessary. We only need two semaphores.
One to tell waiters to wake up and one to let the last waiter that
wakes up notify xshmfence_trigger() it may now return.
diffstat:
x11/libxshmfence/Makefile | 4 +-
x11/libxshmfence/files/xshmfence_semaphore.c | 100 ++++++++++----------------
x11/libxshmfence/files/xshmfence_semaphore.h | 9 +-
3 files changed, 47 insertions(+), 66 deletions(-)
diffs (233 lines):
diff -r ffeb9a8f7a9b -r b9732f0e4152 x11/libxshmfence/Makefile
--- a/x11/libxshmfence/Makefile Sun Feb 23 22:37:54 2020 +0000
+++ b/x11/libxshmfence/Makefile Sun Feb 23 22:47:47 2020 +0000
@@ -1,7 +1,7 @@
-# $NetBSD: Makefile,v 1.13 2020/01/18 23:35:54 rillig Exp $
+# $NetBSD: Makefile,v 1.14 2020/02/23 22:47:47 tnn Exp $
DISTNAME= libxshmfence-1.3
-PKGREVISION= 1
+PKGREVISION= 2
CATEGORIES= x11
MASTER_SITES= ${MASTER_SITE_XORG:=lib/}
EXTRACT_SUFX= .tar.bz2
diff -r ffeb9a8f7a9b -r b9732f0e4152 x11/libxshmfence/files/xshmfence_semaphore.c
--- a/x11/libxshmfence/files/xshmfence_semaphore.c Sun Feb 23 22:37:54 2020 +0000
+++ b/x11/libxshmfence/files/xshmfence_semaphore.c Sun Feb 23 22:47:47 2020 +0000
@@ -35,10 +35,10 @@
static sem_t *mksemtemp(char *, size_t, const char *);
-#define LOCK() do {} while (sem_wait(f->lock) != 0)
-#define UNLOCK() do { sem_post(f->lock); } while (0)
-#define COND_WAIT() do {} while (sem_wait(f->cond) != 0)
-#define COND_SIGNAL() do { sem_post(f->cond); } while (0)
+#define COND_WAIT_W() do {} while (sem_wait(f->cond_w) != 0)
+#define COND_SIGNAL_W() do { sem_post(f->cond_w); } while (0)
+#define COND_WAIT_T() do {} while (sem_wait(f->cond_t) != 0)
+#define COND_SIGNAL_T() do { sem_post(f->cond_t); } while (0)
/**
* xshmfence_trigger:
@@ -52,30 +52,23 @@
int
xshmfence_trigger(struct xshmfence *f) {
int v, waiting;
- LOCK();
v = __sync_bool_compare_and_swap(&f->triggered, 0, 1);
if (v == 0) {
/* already triggered */
- UNLOCK();
return 0;
}
-
- waiting = __sync_fetch_and_add(&f->waiting, 0);
- while (waiting > 0) {
- COND_SIGNAL();
- waiting--;
+ while ((waiting = __sync_fetch_and_add(&f->waiting, 0)) > 0) {
+ if (__sync_bool_compare_and_swap(&f->waiting, waiting, 0)) {
+ __sync_fetch_and_add(&f->wakeups, waiting);
+ while (waiting--) {
+ COND_SIGNAL_W();
+ }
+ COND_WAIT_T();
+ return 0;
+ }
}
- while (__sync_fetch_and_add(&f->waiting, 0) > 0) {
- /*
- * Busy wait until they all woke up.
- * No new sleepers should arrive since
- * the lock is still held.
- */
- /* yield(); */
- }
- UNLOCK();
return 0;
}
@@ -92,24 +85,18 @@
int
xshmfence_await(struct xshmfence *f) {
- LOCK();
if (__sync_fetch_and_add(&f->triggered, 0) == 1) {
- UNLOCK();
return 0;
}
do {
__sync_fetch_and_add(&f->waiting, 1);
- /*
- * These next operations are not atomic.
- * But we busy-wait in xshmfence_trigger, so that's ok.
- */
- UNLOCK();
- COND_WAIT();
- __sync_fetch_and_sub(&f->waiting, 1);
- LOCK();
+ COND_WAIT_W();
+ } while (__sync_fetch_and_add(&f->triggered, 0) == 0);
+
+ if (__sync_sub_and_fetch(&f->wakeups, 1) == 0) {
+ COND_SIGNAL_T();
}
- while (__sync_fetch_and_add(&f->triggered, 0) == 0);
- UNLOCK();
+
return 0;
}
@@ -121,11 +108,7 @@
**/
int
xshmfence_query(struct xshmfence *f) {
- int ret;
- LOCK();
- ret = __sync_fetch_and_add(&f->triggered, 0);
- UNLOCK();
- return ret;
+ return __sync_fetch_and_add(&f->triggered, 0);
}
/**
@@ -137,9 +120,7 @@
**/
void
xshmfence_reset(struct xshmfence *f) {
- LOCK();
__sync_bool_compare_and_swap(&f->triggered, 1, 0);
- UNLOCK();
}
/**
@@ -151,27 +132,26 @@
void
xshmfence_init(int fd)
{
- sem_t *lock;
- sem_t *cond;
+ sem_t *cond_w, *cond_t;
struct xshmfence f;
__sync_fetch_and_and(&f.refcnt, 0);
__sync_fetch_and_and(&f.triggered, 0);
__sync_fetch_and_and(&f.waiting, 0);
-
- lock = mksemtemp(f.lockname, sizeof(f.lockname), "l");
- if (lock == SEM_FAILED) {
+ __sync_fetch_and_and(&f.wakeups, 0);
+
+ cond_w = mksemtemp(f.condname_w, sizeof(f.condname_w), "w");
+ if (cond_w == SEM_FAILED) {
+ err(EXIT_FAILURE, "xshmfence_init: sem_open");
+ }
+ cond_t = mksemtemp(f.condname_t, sizeof(f.condname_t), "t");
+ if (cond_t == SEM_FAILED) {
err(EXIT_FAILURE, "xshmfence_init: sem_open");
}
- cond = mksemtemp(f.condname, sizeof(f.condname), "c");
- if (cond == SEM_FAILED) {
- err(EXIT_FAILURE, "xshmfence_init: sem_open");
- }
-
- sem_close(lock);
- sem_close(cond);
-
+ sem_close(cond_w);
+ sem_close(cond_t);
+
pwrite(fd, &f, sizeof(f), 0);
}
@@ -187,7 +167,7 @@
/*
* map process local memory to page 2
*/
- if (mmap ((void*)&f->lock,
+ if (mmap ((void*)&f->cond_w,
LIBXSHM_PAGESIZE,
PROT_READ|PROT_WRITE,
MAP_FIXED|MAP_ANON,
@@ -195,11 +175,11 @@
errx(EXIT_FAILURE, "xshmfence_open_semaphore: mmap failed");
}
- if ((f->lock = sem_open(f->lockname, 0 , 0)) == SEM_FAILED) {
+ if ((f->cond_w = sem_open(f->condname_w, 0)) == SEM_FAILED) {
errx(EXIT_FAILURE, "xshmfence_open_semaphore: sem_open failed");
}
- if ((f->cond = sem_open(f->condname, 0 , 0)) == SEM_FAILED) {
+ if ((f->cond_t = sem_open(f->condname_t, 0)) == SEM_FAILED) {
errx(EXIT_FAILURE, "xshmfence_open_semaphore: sem_open failed");
}
__sync_fetch_and_add(&f->refcnt, 1);
@@ -214,11 +194,11 @@
void
xshmfence_close_semaphore(struct xshmfence *f)
{
- sem_close(f->lock);
- sem_close(f->cond);
+ sem_close(f->cond_w);
+ sem_close(f->cond_t);
if (__sync_sub_and_fetch(&f->refcnt, 1) == 0) {
- sem_unlink(f->lockname);
- sem_unlink(f->condname);
+ sem_unlink(f->condname_w);
+ sem_unlink(f->condname_t);
}
}
@@ -231,7 +211,7 @@
for(;;) {
if (snprintf(name, namelen, "/xshmf%s-%d", suffix, p) >= namelen)
return SEM_FAILED;
- ret = sem_open(name, O_CREAT|O_EXCL, 0600, 1);
+ ret = sem_open(name, O_CREAT|O_EXCL, 0600, 0);
if (ret == SEM_FAILED) {
if (errno == EEXIST) {
p++;
diff -r ffeb9a8f7a9b -r b9732f0e4152 x11/libxshmfence/files/xshmfence_semaphore.h
--- a/x11/libxshmfence/files/xshmfence_semaphore.h Sun Feb 23 22:37:54 2020 +0000
+++ b/x11/libxshmfence/files/xshmfence_semaphore.h Sun Feb 23 22:47:47 2020 +0000
@@ -43,11 +43,12 @@
int refcnt LOCK_ALIGN;
int triggered LOCK_ALIGN;
int waiting LOCK_ALIGN;
- char lockname[16];
- char condname[16];
+ int wakeups LOCK_ALIGN;
+ char condname_w[16];
+ char condname_t[16];
/* page 2*/
- sem_t *lock PAGE_ALIGN;
- sem_t *cond;
+ sem_t *cond_w PAGE_ALIGN;
+ sem_t *cond_t;
};
void
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