[OpenAFS] Re: bonnie++ on OpenAFS

[Derrick Brashear]

On Tue, Nov 23, 2010 at 6:23 AM, Simon Wilkinson <sxw@inf.ed.ac.uk> wrote:
>
>
> On 23 Nov 2010, at 11:02, Hartmut Reuter <reuter@rzg.mpg.de> wrote:
>>
>> The problem here ist that afs_DoPartialWrite is called with each write. Normally it gets out without doing anything, but if the percentage of dirty chunks is to high it triggers a background store.
>
> On master, at last DoPartialWrite does an immediate store - the only place we can do a background write is in response to a normal close request.
>
> In any case, this problem arises regardless of how we're storing the file. The issue is that our cache eviction strategy picks the most recently accessed chunk to evict, and then we dirty that chunk again immediately after we've flushed it.
>
> 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.

even at that, we did have the opportunity to try to evict earlier
chunks, but things can now get better in head; (and 1.6)



-- 
Derrick