kern/124360: Add ZFS tunable

[Cy Schubert]

>Number:         124360
>Category:       kern
>Synopsis:       Add ZFS tunable
>Confidential:   no
>Severity:       non-critical
>Priority:       low
>Responsible:    freebsd-bugs
>State:          open
>Quarter:        
>Keywords:       
>Date-Required:
>Class:          change-request
>Submitter-Id:   current-users
>Arrival-Date:   Fri Jun 06 20:10:00 UTC 2008
>Closed-Date:
>Last-Modified:
>Originator:     Cy Schubert
>Release:        FreeBSD-2.0
>Organization:
FreeBSD
>Environment:
System: FreeBSD cwsys 7.0-STABLE FreeBSD 7.0-STABLE #0: Mon Jun 2 18:59:51 PDT 2008 root at cwsys:/export/obj/opt/src/cvs-stable7/src/sys/KOMQUATS i386


>Description:
In order to assist tuning ZFS, add the tunable vfs.zfs.vdev.cache.bshift,
base 2 logarithm of the size used to read disks, simlar to the Solaris
/etc/system tunable.

>How-To-Repeat:
N/A
>Fix:

Index: sys/cddl/contrib/opensolaris/uts/common/fs/zfs/vdev_cache.c
===================================================================
RCS file: /home/ncvs/src/sys/cddl/contrib/opensolaris/uts/common/fs/zfs/vdev_cache.c,v
retrieving revision 1.3
diff -u -r1.3 vdev_cache.c
--- sys/cddl/contrib/opensolaris/uts/common/fs/zfs/vdev_cache.c	28 Mar 2008 22:16:10 -0000	1.3
+++ sys/cddl/contrib/opensolaris/uts/common/fs/zfs/vdev_cache.c	6 Jun 2008 18:14:46 -0000
@@ -84,6 +84,9 @@
 TUNABLE_INT("vfs.zfs.vdev.cache.size", &zfs_vdev_cache_size);
 SYSCTL_INT(_vfs_zfs_vdev_cache, OID_AUTO, size, CTLFLAG_RDTUN,
     &zfs_vdev_cache_size, 0, "Size of VDEV cache");
+TUNABLE_INT("vfs.zfs.vdev.cache.bshift", &zfs_vdev_cache_bshift);
+SYSCTL_INT(_vfs_zfs_vdev_cache, OID_AUTO, bshift, CTLFLAG_RDTUN,
+    &zfs_vdev_cache_bshift, 0, "Base 2 logarithm of the size used to read disks");
 
 #define	VCBS (1 << zfs_vdev_cache_bshift)
 


>Release-Note:
>Audit-Trail:
>Unformatted: