[src/trunk]: src/sys/kern - Avoid thundering herd: cv_broadcast(&bp->b_busy) ...

[ad <ad%NetBSD.org@localhost>]

details:   https://anonhg.NetBSD.org/src/rev/608859097a6b
branches:  trunk
changeset: 465996:608859097a6b
user:      ad <ad%NetBSD.org@localhost>
date:      Sun Dec 08 19:26:05 2019 +0000

description:
- Avoid thundering herd: cv_broadcast(&bp->b_busy) -> cv_signal(&bp->b_busy)
- Sprinkle __cacheline_aligned.

diffstat:

 sys/kern/vfs_bio.c |  14 +++++++-------
 1 files changed, 7 insertions(+), 7 deletions(-)

diffs (51 lines):

diff -r 3b24381d447c -r 608859097a6b sys/kern/vfs_bio.c
--- a/sys/kern/vfs_bio.c        Sun Dec 08 19:23:51 2019 +0000
+++ b/sys/kern/vfs_bio.c        Sun Dec 08 19:26:05 2019 +0000
@@ -1,7 +1,7 @@
-/*     $NetBSD: vfs_bio.c,v 1.279 2019/08/26 10:24:39 msaitoh Exp $    */
+/*     $NetBSD: vfs_bio.c,v 1.280 2019/12/08 19:26:05 ad Exp $ */
 
 /*-
- * Copyright (c) 2007, 2008, 2009 The NetBSD Foundation, Inc.
+ * Copyright (c) 2007, 2008, 2009, 2019 The NetBSD Foundation, Inc.
  * All rights reserved.
  *
  * This code is derived from software contributed to The NetBSD Foundation
@@ -123,7 +123,7 @@
  */
 
 #include <sys/cdefs.h>
-__KERNEL_RCSID(0, "$NetBSD: vfs_bio.c,v 1.279 2019/08/26 10:24:39 msaitoh Exp $");
+__KERNEL_RCSID(0, "$NetBSD: vfs_bio.c,v 1.280 2019/12/08 19:26:05 ad Exp $");
 
 #ifdef _KERNEL_OPT
 #include "opt_bufcache.h"
@@ -184,7 +184,7 @@
        uint64_t bq_bytes;
        buf_t *bq_marker;
 };
-static struct bqueue bufqueues[BQUEUES];
+static struct bqueue bufqueues[BQUEUES] __cacheline_aligned;
 
 /* Function prototypes */
 static void buf_setwm(void);
@@ -237,8 +237,8 @@
 /*
  * Buffer queue lock.
  */
-kmutex_t bufcache_lock;
-kmutex_t buffer_lock;
+kmutex_t bufcache_lock __cacheline_aligned;
+kmutex_t buffer_lock __cacheline_aligned;
 
 /* Software ISR for completed transfers. */
 static void *biodone_sih;
@@ -1140,7 +1140,7 @@
        /* Unlock the buffer. */
        CLR(bp->b_cflags, BC_AGE|BC_BUSY|BC_NOCACHE);
        CLR(bp->b_flags, B_ASYNC);
-       cv_broadcast(&bp->b_busy);
+       cv_signal(&bp->b_busy);
 
        if (bp->b_bufsize <= 0)
                brele(bp);