[OpenAFS] Re: bonnie++ on OpenAFS

Marc Dionne marc.c.dionne@gmail.com
Tue, 23 Nov 2010 09:49:58 -0500

On Tue, Nov 23, 2010 at 9:15 AM, Andrew Deason <adeason@sinenomine.net> wrote:
> On Tue, 23 Nov 2010 11:23:03 +0000
> Simon Wilkinson <sxw@inf.ed.ac.uk> wrote:
>> We need a better solution to cache eviction. The problem is that,
>> until very recently, we didn't have the means for one process to
>> successfully flush files written by a different process.
> I'm not following you; why can the cache truncate daemon not be
> triggered and waited for, like in normal cache shortage conditions?

a) I'm pretty sure the cache truncate daemon simply skips dirty chunks
and doesn't do any writeback to the server.
b) The truncate daemon only looks at cache usage, not at dirtiness.
So we can be above the threshold where doPartialWrite will insist on
writing back data (2/3 of cache chunks dirty), but the cache is still
well below the threshold where the truncate daemon will start to
shrink (95% chunks or 90% space I think)