Re: kern/158197: [geom] geom_cache with size> 1000 leads to panics

The following reply was made to PR kern/158197; it has been noted by GNATS.

From: "Pavel Polyakov" <bsd <at> kobyla.org>
To: bug-followup <at> freebsd.org, bsd <at> kobyla.org
Cc: ru <at> freebsd.org
Subject: Re: kern/158197: [geom] geom_cache with size&gt;1000 leads to panics
Date: Mon, 06 Aug 2012 12:54:53 +0300

 Increasing kern.geom.cache.timeout sysctl (from 10 to 30-40 secs) rises  
 the panic risk.
 Increasing the block size forces cache usage & overfill.
 Problem mostly appears after number of CacheFull events, cache memory  
 release and filling it again with read operations.

 So sometimes such situation comes (Entries > Size!):

 # gcache list usr0
 Geom name: usr0
 WroteBytes: 2001752576
 Writes: 93866
 CacheFull: 65
 CacheMisses: 1387
 CacheHits: 4120
 CacheReadBytes: 22902272
 CacheReads: 5442
 ReadBytes: 27303424
 Reads: 6262
 InvalidEntries: 0
 UsedEntries: 0
 Entries: 1025