Author: ivoras
Date: Mon Aug 9 22:22:46 2010
New Revision: 211123
URL: http://svn.freebsd.org/changeset/base/211123
Log:
Elaborate on how hirunningspace was chosen.
Modified:
head/sys/kern/vfs_bio.c
Modified: head/sys/kern/vfs_bio.c
==============================================================================
--- head/sys/kern/vfs_bio.c Mon Aug 9 22:22:06 2010 (r211122)
+++ head/sys/kern/vfs_bio.c Mon Aug 9 22:22:46 2010 (r211123)
@@ -622,8 +622,11 @@ bufinit(void)
/*
* Note: The 16 MB upper limit for hirunningspace was chosen
- * arbitrarily and may need further tuning. The lower 1 MB
- * limit is the historical upper limit for hirunningspace.
+ * arbitrarily and may need further tuning. It corresponds to
+ * 128 outstanding write IO requests (if IO size is 128 KiB),
+ * which fits with many RAID controllers' tagged queing limits.
+ * The lower 1 MB limit is the historical upper limit for
+ * hirunningspace.
*/
hirunningspace = lmax(lmin(roundup(hibufspace / 64, MAXBSIZE),
16 * 1024 * 1024), 1024 * 1024);
_______________________________________________
svn-src-all@freebsd.org mailing list
http://lists.freebsd.org/mailman/listinfo/svn-src-all
To unsubscribe, send any mail to "svn-src-all-unsubscr...@freebsd.org"
