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Replace the ktrace queue's semaphore with a condition variable instead as

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it is slightly more efficient since we already have a mutex to protect the
queue.  Ktrace originally used a semaphore more as a proof of concept.
This commit is contained in:
jhb 2004-02-26 19:30:22 +00:00
parent 9facd5e1d4
commit b9e0b0f9af
1 changed files with 5 additions and 5 deletions
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10
sys/kern/kern_ktrace.c
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@ -53,7 +53,6 @@ __FBSDID("$FreeBSD$");
#include <sys/unistd.h>
#include <sys/vnode.h>
#include <sys/ktrace.h>
#include <sys/sema.h>
#include <sys/sx.h>
#include <sys/sysctl.h>
#include <sys/syslog.h>
@ -107,7 +106,7 @@ SYSCTL_UINT(_kern_ktrace, OID_AUTO, genio_size, CTLFLAG_RW, &ktr_geniosize,
static int print_message = 1;
struct mtx ktrace_mtx;
static struct sema ktrace_sema;
static struct cv ktrace_cv;
static void ktrace_init(void *dummy);
static int sysctl_kern_ktrace_request_pool(SYSCTL_HANDLER_ARGS);
@ -128,7 +127,7 @@ ktrace_init(void *dummy)
int i;
mtx_init(&ktrace_mtx, "ktrace", NULL, MTX_DEF | MTX_QUIET);
sema_init(&ktrace_sema, 0, "ktrace");
cv_init(&ktrace_cv, "ktrace");
STAILQ_INIT(&ktr_todo);
STAILQ_INIT(&ktr_free);
for (i = 0; i < ktr_requestpool; i++) {
@ -262,8 +261,8 @@ ktr_submitrequest(struct ktr_request *req)
mtx_lock(&ktrace_mtx);
STAILQ_INSERT_TAIL(&ktr_todo, req, ktr_list);
cv_signal(&ktrace_cv);
mtx_unlock(&ktrace_mtx);
sema_post(&ktrace_sema);
curthread->td_pflags &= ~TDP_INKTRACE;
}
@ -295,8 +294,9 @@ ktr_loop(void *dummy)
td = curthread;
cred = td->td_ucred;
for (;;) {
sema_wait(&ktrace_sema);
mtx_lock(&ktrace_mtx);
while (STAILQ_EMPTY(&ktr_todo))
cv_wait(&ktrace_cv, &ktrace_mtx);
req = STAILQ_FIRST(&ktr_todo);
STAILQ_REMOVE_HEAD(&ktr_todo, ktr_list);
KASSERT(req != NULL, ("got a NULL request"));