[Gluster-devel] successive bonnie++ tests taking longer and longer to run (system load steadily increasing)

[Raghavendra G]

On Thu, Feb 25, 2010 at 1:38 PM, Daniel Maher
<dma+gluster at witbe.net<dma%2Bgluster at witbe.net>
> wrote:

> Raghavendra G wrote:
>
>> Hi Daniel,
>>
>> Can you decrease the cache size in io-cache (say to 128MB)? If the files
>> being served are bigger than this size, you can as well remove io-cache from
>> configuration. Do let us know if this solves your issue.
>>
>
> Some of the files that are generated during the test are under 128M, and
> some are much larger - effectively, the test deals with larger and larger
> sets of data as it runs its course.
>
> At your suggestion, i changed the io-cache size from the default setting
> (as generated by the configurator) to 128M, and re-ran the test.  The
> results are now much more consistent with what would be expected :
>
> real    21m31.019s
> real    21m30.932s
> real    21m28.965s
> real    21m26.095s
> real    21m26.388s
> real    21m29.377s
> real    21m32.180s
> real    21m26.600s
> real    21m28.354s
> (cut for brevity)
>
> However, at two points during the multi-day test run, something strange
> happened.  The time to completion dropped _dramatically_, and stayed there
> for numerous iterations, before jumping back up again :
>

Mostly reads are being served from io-cache?


>
> real    21m27.806s
> real    21m45.434s
> real    14m41.468s
> real    12m41.172s
> real    12m39.779s
> real    12m34.595s
> real    12m42.223s
> real    12m41.111s
> (repeat 30 iterations)
> real    12m40.185s
> real    12m40.517s
> real    13m25.394s
> real    21m26.375s
> real    21m28.476s
>
> I am forced to assume that something else on either the client or the
> server nodes caused this behaviour, but i cannot imagine what.  The nodes,
> frankly, aren't doing anything else.  Very strange.
>
> I am going to remove the io-cache entirely and see what, if any, effect
> that has.
>
>
> --
> Daniel Maher <dma+gluster AT witbe DOT net>
>
>
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-- 
Raghavendra G
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