Module Name: src
Committed By: hannken
Date: Mon Apr 16 20:25:21 UTC 2018
Modified Files:
src/sys/kern: subr_pserialize.c
Log Message:
Function pserialize_perform() usually succeeds after two cross calls
so defer kpause() to iterations three and above.
Speeds up VOP_REVOKE() on /proc/XXX/status by a factor of ~12.
Ok: core@
To generate a diff of this commit:
cvs rdiff -u -r1.10 -r1.11 src/sys/kern/subr_pserialize.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/subr_pserialize.c
diff -u src/sys/kern/subr_pserialize.c:1.10 src/sys/kern/subr_pserialize.c:1.11
--- src/sys/kern/subr_pserialize.c:1.10 Thu Dec 28 03:39:48 2017
+++ src/sys/kern/subr_pserialize.c Mon Apr 16 20:25:21 2018
@@ -1,4 +1,4 @@
-/* $NetBSD: subr_pserialize.c,v 1.10 2017/12/28 03:39:48 msaitoh Exp $ */
+/* $NetBSD: subr_pserialize.c,v 1.11 2018/04/16 20:25:21 hannken Exp $ */
/*-
* Copyright (c) 2010, 2011 The NetBSD Foundation, Inc.
@@ -38,7 +38,7 @@
*/
#include <sys/cdefs.h>
-__KERNEL_RCSID(0, "$NetBSD: subr_pserialize.c,v 1.10 2017/12/28 03:39:48 msaitoh Exp $");
+__KERNEL_RCSID(0, "$NetBSD: subr_pserialize.c,v 1.11 2018/04/16 20:25:21 hannken Exp $");
#include <sys/param.h>
@@ -146,6 +146,7 @@ pserialize_destroy(pserialize_t psz)
void
pserialize_perform(pserialize_t psz)
{
+ int n;
uint64_t xc;
KASSERT(!cpu_intr_p());
@@ -176,6 +177,7 @@ pserialize_perform(pserialize_t psz)
TAILQ_INSERT_TAIL(&psz_queue0, psz, psz_chain);
psz_work_todo++;
+ n = 0;
do {
mutex_spin_exit(&psz_lock);
@@ -183,9 +185,10 @@ pserialize_perform(pserialize_t psz)
* Force some context switch activity on every CPU, as
* the system may not be busy. Pause to not flood.
*/
+ if (n++ > 1)
+ kpause("psrlz", false, 1, NULL);
xc = xc_broadcast(XC_HIGHPRI, (xcfunc_t)nullop, NULL, NULL);
xc_wait(xc);
- kpause("psrlz", false, 1, NULL);
mutex_spin_enter(&psz_lock);
} while (!kcpuset_iszero(psz->psz_target));
