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From Brian Pane <bp...@pacbell.net>
Subject Re: [PATCH/CONTRIB] Shared Mem Hash Table
Date Fri, 06 Jul 2001 20:25:36 GMT
Ian Holsman wrote:

>On 05 Jul 2001 22:59:25 +0100, David Reid wrote:
>
>>OK, to comment on this prior to the patch being posted...
>>
>>I have SMS running as pools and the implementation I have manages to run the
>>server at 80% of the speed of pools.  This is with no changes to the httpd
>>code except using --enable-sms on the configure line.  Now, this isn't
>>amazing, but does present a starting point.  As I said we haven't started
>>optimising or altering.
>>
[...]

>If you post your patch, I'll run it through quantify which should
>highlight where the bottlenecks are.
>
Detailed profile data from Quantify would be extremely useful--not
just for the new SMS-based pools, but also for APR and the httpd in
general.

This morning, I instrumented the latest httpd-2.0 souce and found that
it's spending 41% of its CPU time in usr mode and 59% in sys when
delivering a 50KB, non-server-parsed file (on Linux, using sendfile).
For server-parsed requests, I've seen ratios as high as 70% usr, 30% sys.

The bad news: the httpd is wasting a huge amount of CPU time in
user-space code (for an optimal httpd serving static files, the usr CPU
should approach zero; 41% is surprisingly high).  The good news: there's
an opportunity to cut the httpd's CPU utilization nearly in half by
tuning just the user-space code.

--Brian



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