strange performance differences of 1.2.2 vs 1.2.5
Chris Goffinet
goffinet at yahoo-inc.com
Mon Jun 2 00:57:19 UTC 2008
Excellent. I will try this on Monday and see where we go. I do believe
we were using libevent 1.3e on FreeBSD (if not 1.3b for sure)
--
Chris Goffinet
MyBlogLog Senior Performance Engineer
Yahoo!
San Francisco, CA
United States
On Jun 1, 2008, at 4:30 PM, Sean Chittenden wrote:
>> That's a good guess (Brian? You know about that?:) ... but a bit
>> doubtful.
>>
>> That gettimeofday(2) call that was changed is only made once per
>> second
>> asyncronously. In order to have such a large performance impact
>> we'd be
>> looking at some more broad changes.
>
> Hrm.... yeah, it's wrapped in an evtimer_set(3) call. Wait...
>
> libevent(3's gettime() static function will use gettimeofday(2) if
> either HAVE_CLOCK_GETTIME and CLOCK_MONOTONIC aren't defined and
> use_monotonic is false. Chris, I haven't profiled anything but it
> may be worth looking into upgrading libevent(3) since it seems as
> though the gettimeofday(2)/gettime() foo was still being toyed with
> around the timeframe of libevent 1.3. YMMV as this was only a
> passing glance at the problem w/ the details provided. :~)
> gprof(1) memcached(8) if you want more specific guidance as to what
> it could be. -sc
>
>
> Stack:
>
> libevent(3)
> event_base_loop(3)
> timeout_correct()
> gettime()
>
>
> --
> Sean Chittenden
> sean at chittenden.org
>
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