Re: select loop speed

From: Duane Wessels <>
Date: Mon, 04 May 1998 10:34:06 -0600

Bill Wichers writes:

>Is there any way to speed up the time spent dealing with select? Cachemgr
> Select loop called: 885025 times, 714.176 ms avg
>on one of my small machines (actually my 1.2.beta20 test box). I've always
>seen VERY fast select times on Alphas and such and slower times on slower
>processors which makes me think that this is primarily a hardware-dictated
>number. Is there any config tweak that can be done to help though? Or
>would I just need to beef up the processor...

Dancer's comments were correct. We simply count the number of times
select was called, and divide the total process running time by the
number of select calls.

This means, on average it takes your cache .714 seconds to check all
the open file descriptors once. But this also includes time select()
spends in a wait state when there is no I/O on any file descriptors.
My relatively idle workstation cache has similar numbers:

        Select loop called: 336782 times, 715.938 ms avg

But my busy caches have are much lower:

        Select loop called: 16940436 times, 10.427 ms avg
        Select loop called: 80524058 times, 10.030 ms avg
        Select loop called: 10590369 times, 8.675 ms avg
        Select loop called: 84319441 times, 9.578 ms avg

Duane W.
Received on Mon May 04 1998 - 09:41:11 MDT

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