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From: Jung-uk Kim <jkim@FreeBSD.org>
Date: Wed, 15 Oct 2014 19:46:50 +0000 (UTC)
To: src-committers@freebsd.org, svn-src-all@freebsd.org,
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Subject: svn commit: r273148 - stable/9/sys/kern
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Author: jkim
Date: Wed Oct 15 19:46:49 2014
New Revision: 273148
URL: https://svnweb.freebsd.org/changeset/base/273148

Log:
  Make kern.nswbuf tunable from loader.

Modified:
  stable/9/sys/kern/vfs_bio.c
Directory Properties:
  stable/9/sys/   (props changed)

Modified: stable/9/sys/kern/vfs_bio.c
==============================================================================
--- stable/9/sys/kern/vfs_bio.c	Wed Oct 15 19:41:51 2014	(r273147)
+++ stable/9/sys/kern/vfs_bio.c	Wed Oct 15 19:46:49 2014	(r273148)
@@ -520,6 +520,10 @@ bd_speedup(void)
 	mtx_unlock(&bdlock);
 }
 
+#ifndef NSWBUF_MIN
+#define	NSWBUF_MIN	16
+#endif
+
 #ifdef __i386__
 #define	TRANSIENT_DENOM	5
 #else
@@ -631,11 +635,10 @@ kern_vfs_bio_buffer_alloc(caddr_t v, lon
 	 * swbufs are used as temporary holders for I/O, such as paging I/O.
 	 * We have no less then 16 and no more then 256.
 	 */
-	nswbuf = max(min(nbuf/4, 256), 16);
-#ifdef NSWBUF_MIN
+	nswbuf = min(nbuf / 4, 256);
+	TUNABLE_INT_FETCH("kern.nswbuf", &nswbuf);
 	if (nswbuf < NSWBUF_MIN)
 		nswbuf = NSWBUF_MIN;
-#endif
 #ifdef DIRECTIO
 	ffs_rawread_setup();
 #endif