Subject: Re: 3.0.1: softdep + ffsv2 + 'heavy' load = pauses
To: None <,>
From: Juan RP <>
List: tech-kern
Date: 07/22/2006 23:30:42
On Sat, 22 Jul 2006 16:57:55 -0400
Thor Lancelot Simon <> wrote:

> There are a few approaches you can take to make this problem less annoying.
> You can get a disk I/O subsystem with a large write-back cache and the
> ability to enqueue multiple read operations at once so that it can bypass
> reads around writes.  These are often expensive (think hardware RAID
> controller with cache battery).  Or you can tweak DIRDELAY and METADELAY
> in the softdep code to make the potential backlog smaller and flush it
> to disk much more often.  Or you can limit the metadata cache at a smaller
> size -- this is probably the worst approach.

With -current, you can tweak syncer's delay options via sysctl (vfs.sync.*).