Messages in this thread | | | Date | Fri, 2 Apr 2004 16:10:22 -0800 | From | Mark Wong <> | Subject | Re: 2.6.5-rc3-mm4 |
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On Sat, Apr 03, 2004 at 09:43:57AM +1000, Nick Piggin wrote: > 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.
Whoops, I changed when the sample is take. This 2.6.3 results samples when the test is ramping up, while all the subsequent tests are sampling after the test ramps up. I can redo this one.
> 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?
Yeah, I did tests previously to determine what might be the cause and Andrew believes it's the CPU scheduler. - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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