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    SubjectRe: 2.6.5-rc3-mm4
    Andrew Morton wrote:
    > markw@osdl.org wrote:
    >
    >>I reran DBT-2 to with ext2 and ext3 (in case you were still interested)
    >> on my 4-way Xeon system with 60+ drives:
    >> http://developer.osdl.org/markw/fs/dbt2_project_results.html
    >>
    >> Aside from the from the drop you're already aware of since 2.6.3, it
    >> looks like DBT-2 takes another smaller hit after 2.6.5-rc3-mm2. Here's
    >> a brief summary from the link above:
    >
    >
    > The profile is interesting:
    >
    > 3671973 poll_idle 63309.8793
    > 77750 __copy_from_user_ll 637.2951
    > 64788 generic_unplug_device 487.1278
    > 62968 DAC960_LP_InterruptHandler 336.7273
    > 53908 finish_task_switch 361.7987
    > 52947 __copy_to_user_ll 441.2250
    > 29419 dm_table_unplug_all 439.0896
    > 25947 __make_request 17.9938
    > 18564 dm_table_any_congested 199.6129
    > 13785 update_queue 104.4318
    > 13498 try_to_wake_up 20.3590
    > 12736 __wake_up 114.7387
    > 12560 kmem_cache_alloc 163.1169
    > 12221 .text.lock.sched 40.7367
    >
    > - There's a ton of idle time there.
    >
    > - The CPU scheduler is hurting. Nick and Ingo are patching up a storm to
    > fix a similar problem which Jeremy Higdon is observing at 200,000
    > IOs/sec. This will get better.

    Versus this for 2.6.3:

    12825181 poll_idle 221123.8103
    219606 schedule 126.7201
    194233 __copy_from_user_ll 1541.5317
    191707 __copy_to_user_ll 1597.5583
    149704 DAC960_LP_InterruptHandler 800.5561
    120972 generic_unplug_device 822.9388
    87891 __make_request 60.9931
    49207 try_to_wake_up 74.5561
    42647 do_anonymous_page 65.5100

    Which looks like it is taking a lot longer (is it the same test?)
    It is difficult to tell how idle each one is due to lack of total
    ticks reported, but, copy_to/from_user is 3% the amount of idle
    time in 2.6.3, while being 3.5% the amount of idle time in your
    profile.

    So 2.6.3 could be relatively more idle than -mm.

    Do we know what the 2.6.3 regression is caused by? Or is it
    likely to be the CPU scheduler?
    -
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