svn commit: r343330 - stable/12/sys/kern

[Alexander Motin]

Author: mav
Date: Wed Jan 23 00:56:53 2019
New Revision: 343330
URL: https://svnweb.freebsd.org/changeset/base/343330

Log:
  Increase MTX_POOL_SLEEP_SIZE from 128 to 1024.
  
  This value remained unchanged for 15 years, and now this bump reduces
  lock spinning in GEOM and BIO layers while doing ~1.6M IOPS to 4 NVMe
  on 72-core system from ~25% to ~5% by the cost of additional 28KB RAM.
  
  While there, align struct mtx_pool fields to cache lines.

Modified:
  stable/12/sys/kern/kern_mtxpool.c
Directory Properties:
  stable/12/   (props changed)

Modified: stable/12/sys/kern/kern_mtxpool.c
==============================================================================
--- stable/12/sys/kern/kern_mtxpool.c	Wed Jan 23 00:55:57 2019	(r343329)
+++ stable/12/sys/kern/kern_mtxpool.c	Wed Jan 23 00:56:53 2019	(r343330)
@@ -62,14 +62,14 @@ static MALLOC_DEFINE(M_MTXPOOL, "mtx_pool", "mutex poo
 
 /* Pool sizes must be a power of two */
 #ifndef MTX_POOL_SLEEP_SIZE
-#define MTX_POOL_SLEEP_SIZE		128
+#define MTX_POOL_SLEEP_SIZE		1024
 #endif
 
 struct mtxpool_header {
 	int		mtxpool_size;
 	int		mtxpool_mask;
 	int		mtxpool_shift;
-	int		mtxpool_next;
+	int		mtxpool_next __aligned(CACHE_LINE_SIZE);
 };
 
 struct mtx_pool {