[Xapian-discuss] 1.2.2/3 performance issue

[Markus Wörle]

Am 31.08.2010 um 15:56 schrieb Olly Betts:

> On Tue, Aug 31, 2010 at 03:40:17PM +0200, Markus Wörle wrote:
>> Am 31.08.2010 um 15:04 schrieb Olly Betts:
>>> On Tue, Aug 31, 2010 at 02:25:52PM +0200, Markus Wörle wrote:
>>>> Do have any idea yet what change from 1.2.0 to 1.2.2 could have been caused
>>>> the slowdown?
>>> 
>>> If this is on x86 (not x86-64), then try running configure with
>>> --disable-sse.
>>> 
>>> 1.2.1 defaults to use SSE for floating point on x86 (rather than 387
>>> instructions) which avoids issues with excess precision.  In my tests
>>> SSE was actually faster, but I suppose that may vary between CPU models.
>> 
>> It's a x86-64 linux on a Xeon (X5450) based system. I tried it anyway, but
>> --disable-sse did not change anything.
> 
> Indeed - it only does anything on x86.
> 
> Nothing else looks likely.  There are a couples of correctness fixes (tickets
> #475 and #476) but I'd be surprised if they had such a drastic effect.
> 
> You could try 1.2.1, but there were a lot of changes between 1.2.0 and 1.2.1
> and not many between 1.2.1 and 1.2.2, so it's likely 1.2.1 is affected too.
> 
> Beyond hat you could try a binary chop on SVN to find where this started if
> you have a simple case to check each time.

Did that (took a while). It turned out that revision 14612 and below are fast, whereas 14613 and above are slow.

So it's http://trac.xapian.org/changeset/14613 where it happens.

Regards,
mrks