Enable pool cache on knote pool

Use the pool cache to reduce the overhead of memory management in
function kqueue_register().

When EV_ADD is given, kqueue_register() pre-allocates a knote to avoid
potential sleeping in the middle of the critical section that spans
from knote lookup to insertion. However, the pre-allocation is useless
if the lookup finds a matching knote.

The cost of knote allocation will become significant with kqueue-based
poll(2) and select(2) because the frequency of allocation will increase.
Most of the cost appears to come from the locking inside the pool.
The pool cache amortizes it by using CPU-local caches of free knotes
as buffers.

OK dlg@ mpi@

diff --git a/sys/kern/init_main.c b/sys/kern/init_main.c
index 7902f2e..89d6b9d 100644 (file)
--- a/sys/kern/init_main.c
+++ b/sys/kern/init_main.c
@@ -1,4 +1,4 @@
-/*     $OpenBSD: init_main.c,v 1.306 2021/02/08 10:51:01 mpi Exp $     */
+/*     $OpenBSD: init_main.c,v 1.307 2021/06/02 13:56:28 visa Exp $    */
 /*     $NetBSD: init_main.c,v 1.84.4.1 1996/06/02 09:08:06 mrg Exp $   */
 
 /*
@@ -71,6 +71,7 @@
 #include <sys/msg.h>
 #endif
 #include <sys/domain.h>
+#include <sys/event.h>
 #include <sys/msgbuf.h>
 #include <sys/mbuf.h>
 #include <sys/pipe.h>
@@ -148,7 +149,6 @@ void        crypto_init(void);
 void   db_ctf_init(void);
 void   prof_init(void);
 void   init_exec(void);
-void   kqueue_init(void);
 void   futex_init(void);
 void   taskq_init(void);
 void   timeout_proc_init(void);
@@ -432,7 +432,9 @@ main(void *framep)
        prof_init();
 #endif
 
-       mbcpuinit();    /* enable per cpu mbuf data */
+       /* Enable per-CPU data. */
+       mbcpuinit();
+       kqueue_init_percpu();
        uvm_init_percpu();
 
        /* init exec and emul */

diff --git a/sys/kern/kern_event.c b/sys/kern/kern_event.c
index 7f821a6..9884b55 100644 (file)
--- a/sys/kern/kern_event.c
+++ b/sys/kern/kern_event.c
@@ -1,4 +1,4 @@
-/*     $OpenBSD: kern_event.c,v 1.163 2021/04/22 15:30:12 visa Exp $   */
+/*     $OpenBSD: kern_event.c,v 1.164 2021/06/02 13:56:28 visa Exp $   */
 
 /*-
  * Copyright (c) 1999,2000,2001 Jonathan Lemon <jlemon@FreeBSD.org>
@@ -70,7 +70,6 @@
 
 struct kqueue *kqueue_alloc(struct filedesc *);
 void   kqueue_terminate(struct proc *p, struct kqueue *);
-void   kqueue_init(void);
 void   KQREF(struct kqueue *);
 void   KQRELE(struct kqueue *);
 
@@ -231,6 +230,12 @@ kqueue_init(void)
            PR_WAITOK, "knotepl", NULL);
 }
 
+void
+kqueue_init_percpu(void)
+{
+       pool_cache_init(&knote_pool);
+}
+
 int
 filt_fileattach(struct knote *kn)
 {

diff --git a/sys/sys/event.h b/sys/sys/event.h
index 105f7e5..27e9d97 100644 (file)
--- a/sys/sys/event.h
+++ b/sys/sys/event.h
@@ -1,4 +1,4 @@
-/*     $OpenBSD: event.h,v 1.54 2021/02/24 14:59:52 visa Exp $ */
+/*     $OpenBSD: event.h,v 1.55 2021/06/02 13:56:28 visa Exp $ */
 
 /*-
  * Copyright (c) 1999,2000,2001 Jonathan Lemon <jlemon@FreeBSD.org>
@@ -292,6 +292,8 @@ extern void knote_fdclose(struct proc *p, int fd);
 extern void    knote_processexit(struct proc *);
 extern void    knote_modify(const struct kevent *, struct knote *);
 extern void    knote_submit(struct knote *, struct kevent *);
+extern void    kqueue_init(void);
+extern void    kqueue_init_percpu(void);
 extern int     kqueue_register(struct kqueue *kq,
                    struct kevent *kev, struct proc *p);
 extern int     kqueue_scan(struct kqueue_scan_state *, int, struct kevent *,