Bad bind performance with FreeBSD 7
kris at FreeBSD.org
Fri Apr 4 13:31:52 UTC 2008
Attila Nagy wrote:
> On 2008.04.03. 15:21, Stefan Lambrev wrote:
>> Attila Nagy wrote:
>>> On 01/29/08 11:40, Attila Nagy wrote:
>>>> ps: I have an other problem. I've recently switched from a last year
>>>> 6-STABLE to 7-STABLE and got pretty bad results on the same machine
>>>> with the same bind (9.4).
>>>> The graphs are here:
>>> The problem still persists and now I can provide some profiling info,
>>> made by HWPMC.
>> Sorry if you already answer this question, but at least I can find it
>> in the thread.
>> What scheduler are you using on RELENG_7 ?
>> Did you check with both schedulers (ule/4bsd) to see which one works
>> better for you?
>> Also are you sure that you service the same number of requests - I see
>> that the 6.x image shows CPU usage from
>> Aug 2007 and 7.x image is from Jan 2008 ... is it possible, that you
>> have more requests and that's why your CPU usage increased?
> As for the pictures: GENERIC kernels, so 4BSD on both versions (6 and 7).
> As for the profiling info: 4BSD on 6, ULE on 7 (because both were
> upgraded yesterday, and ULE is now default in RELENG_7)
> The pictures are from the same timeframe (what aug 2007 refers to is the
> time when the OS was compiled), the two machines were behind a per
> packet load balancer, so yes: at least in pps, they've got exactly the
> same traffic (of course it was possible be that one machine could serve
> the answer directly from the cache, while the other had to go out, but
> I've started them at the same time, so I think this effect was minimized).
User time is much greater so named is doing much more work for some
reason. It doesn't appear that this is a kernel problem. Verify that
the config is identical, and you are not overloading it (bind doesn't
scale beyond 4 threads).
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