Tuesday, July 29, 2008

Benchmarking is available!

I've begun benchmarking Cacheboy-1.4. The details are available at http://www.cacheboy.net/benchmarks.html. They aren't spectacular - I'm mainly doing them to keep track on development and make sure I'm not introducing regressions anywhere.

I'm not all that happy with 50% CPU (on one CPU too!) at 500 req/sec. Alas, thats what I have to work with - I can't push these disks nor the polygraph hosts any harder at the present time. Maybe if I spent two weeks fixing polygraph so it used kqueue() instead of poll() ..

4 comments:

  1. Hi, have you filled the hard disk cache in these tests ?, I'm wondering, because I have a similar hardware and with %85 hit ratio, I have about 80% CPU utilization once the hard disk cache are filled and they have to recycle.

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  2. This is what the FSes look like:

    /dev/label/AGNUS_DATA_1 34424808 22527384 9143440 71% /local/AGNUS_DATA_1
    /dev/label/AGNUS_DATA_2 34424808 22525928 9144896 71% /local/AGNUS_DATA_2
    /dev/label/AGNUS_DATA_3 34424808 22526056 9144768 71% /local/AGNUS_DATA_3
    /dev/label/AGNUS_DATA_4 34424808 22524688 9146136 71% /local/AGNUS_DATA_4

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  3. I have mine cache_dirs adjusted to only use 50% of the hard disks, this is to prevent the fs fragmentation to affect squid performance.
    But when I reach that 50% and squid starts reclycling space, that's when the high IO and High CPU utilization starts.

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  4. You shouldn't be seeing much higher CPU when the cache recycling code is running.

    Perhaps you need to attach a profiler and see whats taking all the CPU when that occurs.

    Also, if you have a high IOWAIT time (due to sub-par devices/drivers) then the recycling may take more CPU than it would under sensible hardware.

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