Author: mjg
Date: Thu Nov 29 02:52:08 2018
New Revision: 341176
URL: https://svnweb.freebsd.org/changeset/base/341176
Log:
proc: create a dedicated lock for zombproc to ligthen the load on allproc_lock
waitpid always takes proctree to evaluate the list, but only takes allproc
if it can reap. With this patch allproc is no longer taken, which helps during
poudriere -j 128.
Discussed with: kib
Sponsored by: The FreeBSD Foundation
Modified:
head/sys/kern/kern_exit.c
head/sys/kern/kern_fork.c
head/sys/kern/kern_proc.c
head/sys/kern/kern_racct.c
head/sys/sys/proc.h
Modified: head/sys/kern/kern_exit.c
==============================================================================
--- head/sys/kern/kern_exit.c Thu Nov 29 01:31:12 2018 (r341175)
+++ head/sys/kern/kern_exit.c Thu Nov 29 02:52:08 2018 (r341176)
@@ -432,8 +432,10 @@ exit1(struct thread *td, int rval, int signo)
* Move proc from allproc queue to zombproc.
*/
sx_xlock(&allproc_lock);
+ sx_xlock(&zombproc_lock);
LIST_REMOVE(p, p_list);
LIST_INSERT_HEAD(&zombproc, p, p_list);
+ sx_xunlock(&zombproc_lock);
sx_xunlock(&allproc_lock);
/*
@@ -871,9 +873,9 @@ proc_reap(struct thread *td, struct proc *p, int *stat
* Remove other references to this process to ensure we have an
* exclusive reference.
*/
- sx_xlock(&allproc_lock);
+ sx_xlock(&zombproc_lock);
LIST_REMOVE(p, p_list); /* off zombproc */
- sx_xunlock(&allproc_lock);
+ sx_xunlock(&zombproc_lock);
sx_xlock(PIDHASHLOCK(p->p_pid));
LIST_REMOVE(p, p_hash);
sx_xunlock(PIDHASHLOCK(p->p_pid));
Modified: head/sys/kern/kern_fork.c
==============================================================================
--- head/sys/kern/kern_fork.c Thu Nov 29 01:31:12 2018 (r341175)
+++ head/sys/kern/kern_fork.c Thu Nov 29 02:52:08 2018 (r341176)
@@ -238,6 +238,7 @@ fork_findpid(int flags)
struct proc *p;
int trypid;
static int pidchecked = 0;
+ bool locked_zomb = false;
/*
* Requires allproc_lock in order to iterate over the list
@@ -318,6 +319,10 @@ again:
}
if (!doingzomb) {
doingzomb = 1;
+ if (!locked_zomb) {
+ sx_slock(&zombproc_lock);
+ locked_zomb = true;
+ }
p = LIST_FIRST(&zombproc);
goto again;
}
@@ -330,6 +335,9 @@ again:
pidchecked = 0;
else
lastpid = trypid;
+
+ if (locked_zomb)
+ sx_sunlock(&zombproc_lock);
return (trypid);
}
Modified: head/sys/kern/kern_proc.c
==============================================================================
--- head/sys/kern/kern_proc.c Thu Nov 29 01:31:12 2018 (r341175)
+++ head/sys/kern/kern_proc.c Thu Nov 29 02:52:08 2018 (r341176)
@@ -125,6 +125,7 @@ u_long pgrphash;
struct proclist allproc;
struct proclist zombproc;
struct sx __exclusive_cache_line allproc_lock;
+struct sx __exclusive_cache_line zombproc_lock;
struct sx __exclusive_cache_line proctree_lock;
struct mtx __exclusive_cache_line ppeers_lock;
uma_zone_t proc_zone;
@@ -177,6 +178,7 @@ procinit(void)
u_long i;
sx_init(&allproc_lock, "allproc");
+ sx_init(&zombproc_lock, "zombproc");
sx_init(&proctree_lock, "proctree");
mtx_init(&ppeers_lock, "p_peers", NULL, MTX_DEF);
LIST_INIT(&allproc);
@@ -1194,14 +1196,14 @@ zpfind(pid_t pid)
{
struct proc *p;
- sx_slock(&allproc_lock);
+ sx_slock(&zombproc_lock);
LIST_FOREACH(p, &zombproc, p_list) {
if (p->p_pid == pid) {
PROC_LOCK(p);
break;
}
}
- sx_sunlock(&allproc_lock);
+ sx_sunlock(&zombproc_lock);
return (p);
}
Modified: head/sys/kern/kern_racct.c
==============================================================================
--- head/sys/kern/kern_racct.c Thu Nov 29 01:31:12 2018 (r341175)
+++ head/sys/kern/kern_racct.c Thu Nov 29 02:52:08 2018 (r341176)
@@ -1228,11 +1228,13 @@ racctd(void)
sx_slock(&allproc_lock);
+ sx_slock(&zombproc_lock);
LIST_FOREACH(p, &zombproc, p_list) {
PROC_LOCK(p);
racct_set(p, RACCT_PCTCPU, 0);
PROC_UNLOCK(p);
}
+ sx_sunlock(&zombproc_lock);
FOREACH_PROC_IN_SYSTEM(p) {
PROC_LOCK(p);
Modified: head/sys/sys/proc.h
==============================================================================
--- head/sys/sys/proc.h Thu Nov 29 01:31:12 2018 (r341175)
+++ head/sys/sys/proc.h Thu Nov 29 02:52:08 2018 (r341176)
@@ -959,6 +959,7 @@ extern u_long pgrphash;
extern struct sx allproc_lock;
extern int allproc_gen;
+extern struct sx zombproc_lock;
extern struct sx proctree_lock;
extern struct mtx ppeers_lock;
extern struct proc proc0; /* Process slot for swapper. */
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