[OpenAFS] Re: bonnie++ on OpenAFS

Derrick Brashear shadow@gmail.com
Tue, 23 Nov 2010 09:55:26 -0500

On Tue, Nov 23, 2010 at 9:49 AM, Marc Dionne <marc.c.dionne@gmail.com> wrote:
> 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)

nothing precludes us from changing that, but yes, b) is correct and
i'm pretty sure you're right about
a) also.