[OpenAFS] Documentation on fs bypassthreshold?

Matt W. Benjamin matt@linuxbox.com
Mon, 18 Oct 2010 13:29:26 -0400 (EDT)

Hi Phil,

This fs operation gets, or sets, a threshold (relative to file size) for cache bypass.  You need to be using a CM port with bypass support, i.e., Linux right now.  By default, all reads and writes are through the CM's cache.  There is no threshold unless set, so by default cache bypass is not operative.  If you (cm administrator) set a value here, reads on files greater than the threshold size use the cache bypass strategy.  Cache bypass reads are performed in the background queue, into the page cache only.  You probably want to increase CM daemon threads should you enable this.


----- "Phillip Moore" <w.phillip.moore@gmail.com> wrote:

> In 1.5.77, there's no man page for fs_bypassthreshold, and Google's
> not showing much that helps, either.
> Can someone explain to me what this does? For the purposes of
> supporting it in AFS::Command, I only need to know the CLI syntax, and
> I can read venus/fs.c to figure out how to parse the output, but...
> What does it DO?


Matt Benjamin

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