Re: AS performance with reiser4 on 2.6.3

[markw@osdl.org]

On 27 Feb, Hans Reiser wrote:
> Nikita Danilov wrote:
> 
>>markw@osdl.org writes:
>> > Hi Nick,
>> > 
>> > I started getting some results with dbt-2 on 2.6.3 and saw that reiser4
>> > is doing a bit worse with the AS elevator.  Although reiser4 wasn't
>> > doing well to begin with, compared to the other filesystems.  I have
>> > links to the STP results on our 4-ways and 8-ways here:
>> > 	http://developer.osdl.org/markw/fs/dbt2_stp_results.html
>>
>>There were no changes between 2.6.2 and 2.6.3 that could affect reiser4
>>performance, so it is not clear why numbers are so different. Probably
>>results should be averaged over several runs.
>>
> The differences don't "feel" like testing error, and in any event 
> something is seriously wrong.  That something is either poor fsync 
> performance, or poor scalability.  In any event, please investigate, and 
> please try such things as using capture on copy.  Mark, does this 
> benchmark like to use fsync?
> 
> Thanks much mark for bringing this to our attention.

Yes, PostgreSQL uses fsync for its database logging.  I can certainly
enable the capture on copy option.  Does that produce something that I
need to manually capture?

Mark