Module Name: src
Committed By: riastradh
Date: Wed Apr 8 02:49:03 UTC 2015
Modified Files:
src/sys/kern: kern_rndq.c
Log Message:
Gather sample queue and lock into a static cacheline-aligned struct.
To generate a diff of this commit:
cvs rdiff -u -r1.33 -r1.34 src/sys/kern/kern_rndq.c
Please note that diffs are not public domain; they are subject to the
copyright notices on the relevant files.
Modified files:
Index: src/sys/kern/kern_rndq.c
diff -u src/sys/kern/kern_rndq.c:1.33 src/sys/kern/kern_rndq.c:1.34
--- src/sys/kern/kern_rndq.c:1.33 Wed Apr 8 02:44:07 2015
+++ src/sys/kern/kern_rndq.c Wed Apr 8 02:49:03 2015
@@ -1,4 +1,4 @@
-/* $NetBSD: kern_rndq.c,v 1.33 2015/04/08 02:44:07 riastradh Exp $ */
+/* $NetBSD: kern_rndq.c,v 1.34 2015/04/08 02:49:03 riastradh Exp $ */
/*-
* Copyright (c) 1997-2013 The NetBSD Foundation, Inc.
@@ -32,7 +32,7 @@
*/
#include <sys/cdefs.h>
-__KERNEL_RCSID(0, "$NetBSD: kern_rndq.c,v 1.33 2015/04/08 02:44:07 riastradh Exp $");
+__KERNEL_RCSID(0, "$NetBSD: kern_rndq.c,v 1.34 2015/04/08 02:49:03 riastradh Exp $");
#include <sys/param.h>
#include <sys/atomic.h>
@@ -109,11 +109,13 @@ typedef struct _rnd_sample_t {
} rnd_sample_t;
/*
- * The event queue. Fields are altered at an interrupt level.
- * All accesses must be protected with the mutex.
+ * The sample queue. Samples are put into the queue and processed in a
+ * softint in order to limit the latency of adding a sample.
*/
-SIMPLEQ_HEAD(, _rnd_sample_t) rnd_samples;
-kmutex_t rnd_mtx;
+static struct {
+ kmutex_t lock;
+ SIMPLEQ_HEAD(, _rnd_sample_t) q;
+} rnd_samples __cacheline_aligned;
/*
* Memory pool for sample buffers
@@ -522,7 +524,7 @@ rnd_init(void)
if (rnd_ready)
return;
- mutex_init(&rnd_mtx, MUTEX_DEFAULT, IPL_VM);
+ mutex_init(&rnd_samples.lock, MUTEX_DEFAULT, IPL_VM);
rndsinks_init();
/*
@@ -532,7 +534,7 @@ rnd_init(void)
c = rnd_counter();
LIST_INIT(&rnd_sources);
- SIMPLEQ_INIT(&rnd_samples);
+ SIMPLEQ_INIT(&rnd_samples.q);
rndpool_init(&rnd_pool);
mutex_init(&rndpool_mtx, MUTEX_DEFAULT, IPL_VM);
@@ -738,15 +740,15 @@ rnd_detach_source(krndsource_t *source)
* If there are samples queued up "remove" them from the sample queue
* by setting the source to the no-collect pseudosource.
*/
- mutex_spin_enter(&rnd_mtx);
- sample = SIMPLEQ_FIRST(&rnd_samples);
+ mutex_spin_enter(&rnd_samples.lock);
+ sample = SIMPLEQ_FIRST(&rnd_samples.q);
while (sample != NULL) {
if (sample->source == source)
sample->source = &rnd_source_no_collect;
sample = SIMPLEQ_NEXT(sample, next);
}
- mutex_spin_exit(&rnd_mtx);
+ mutex_spin_exit(&rnd_samples.lock);
if (!cpu_softintr_p()) { /* XXX XXX very temporary "fix" */
if (source->state) {
@@ -955,12 +957,12 @@ rnd_add_data_ts(krndsource_t *rs, const
return;
}
- mutex_spin_enter(&rnd_mtx);
+ mutex_spin_enter(&rnd_samples.lock);
while ((state = SIMPLEQ_FIRST(&tmp_samples))) {
SIMPLEQ_REMOVE_HEAD(&tmp_samples, next);
- SIMPLEQ_INSERT_HEAD(&rnd_samples, state, next);
+ SIMPLEQ_INSERT_HEAD(&rnd_samples.q, state, next);
}
- mutex_spin_exit(&rnd_mtx);
+ mutex_spin_exit(&rnd_samples.lock);
/* Cause processing of queued samples */
rnd_schedule_process();
@@ -1040,14 +1042,12 @@ rnd_process_events(void)
SIMPLEQ_HEAD_INITIALIZER(df_samples);
/*
- * Sample queue is protected by rnd_mtx, drain to onstack queue
- * and drop lock.
+ * Drain to the on-stack queue and drop the lock.
*/
-
- mutex_spin_enter(&rnd_mtx);
- while ((sample = SIMPLEQ_FIRST(&rnd_samples))) {
+ mutex_spin_enter(&rnd_samples.lock);
+ while ((sample = SIMPLEQ_FIRST(&rnd_samples.q))) {
found++;
- SIMPLEQ_REMOVE_HEAD(&rnd_samples, next);
+ SIMPLEQ_REMOVE_HEAD(&rnd_samples.q, next);
/*
* We repeat this check here, since it is possible
* the source was disabled before we were called, but
@@ -1061,7 +1061,7 @@ rnd_process_events(void)
SIMPLEQ_INSERT_TAIL(&dq_samples, sample, next);
}
}
- mutex_spin_exit(&rnd_mtx);
+ mutex_spin_exit(&rnd_samples.lock);
/* Don't thrash the rndpool mtx either. Hold, add all samples. */
mutex_spin_enter(&rndpool_mtx);
