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    SubjectRe: RFC on io-stalls patch
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    On Tue, 2003-07-15 at 04:28, Jens Axboe wrote:

    > Definitely, because prepare to be a bit disappointed. Here are scores
    > that include 2.4.21 as well:

    > io_load:
    > Kernel [runs] Time CPU% Loads LCPU% Ratio
    > 2.4.21 3 543 49.7 100.4 19.0 4.08
    > 2.4.22-pre5 3 637 42.5 120.2 18.5 4.75
    > 2.4.22-pre5-axboe 3 540 50.0 103.0 18.1 4.06

    Huh, this is completely different than io_load on my box (2P scsi, ext3,
    data=writeback)

    io_load:
    Kernel [runs] Time CPU% Loads LCPU% Ratio
    2.4.21 3 520 52.5 27.8 15.2 3.80
    2.4.22-pre5 3 394 69.0 21.5 15.4 2.90
    2.4.22-sync 3 321 84.7 16.2 15.8 2.36

    Where 2.4.22-sync was the variant I posted yesterday. I don't really
    see how 2.4.21 can get numbers as good as 2.4.22-pre5 on the io_load
    test, the read starvation with a big streaming io is horrible.

    The data=writeback is changing the workload significantly, I used it
    because I didn't want the data=ordered code to flush all dirty buffers
    every 5 seconds. I would expect ext3 data=ordered to be pretty
    starvation prone in 2.4.21 as well though.

    BTW, the contest run times vary pretty wildy. My 3 compiles with
    io_load running on 2.4.21 were 603s, 443s and 515s. This doesn't make
    the average of the 3 numbers invalid, but we need a more stable metric.

    -chris


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