Messages in this thread | | | Subject | Re: NFS client latencies | From | Lee Revell <> | Date | Wed, 30 Mar 2005 09:26:18 -0500 |
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On Tue, 2005-03-29 at 18:18 -0500, Trond Myklebust wrote: > ty den 29.03.2005 Klokka 18:04 (-0500) skreiv Lee Revell: > > I am seeing long latencies in the NFS client code. Attached is a ~1.9 > > ms latency trace. > > What kind of workload are you using to produce these numbers? >
Here is the other long latency I am seeing in the NFS client. I posted this before, but did not cc: the correct people.
It looks like nfs_wait_on_requests is doing thousands of radix_tree_gang_lookups while holding some lock.
Lee
preemption latency trace v1.1.4 on 2.6.12-rc1-RT-V0.7.41-00 -------------------------------------------------------------------- latency: 3178 �s, #4095/14224, CPU#0 | (M:preempt VP:0, KP:1, SP:1 HP:1 #P:1) ----------------- | task: ksoftirqd/0-2 (uid:0 nice:-10 policy:0 rt_prio:0) -----------------
_------=> CPU# / _-----=> irqs-off | / _----=> need-resched || / _---=> hardirq/softirq ||| / _--=> preempt-depth |||| / ||||| delay cmd pid ||||| time | caller \ / ||||| \ | / (T1/#0) <...> 32105 0 3 00000004 00000000 [0011939614227867] 0.000ms (+4137027.445ms): <6500646c> (<61000000>) (T1/#2) <...> 32105 0 3 00000004 00000002 [0011939614228097] 0.000ms (+0.000ms): __trace_start_sched_wakeup+0x9a/0xd0 <c013150a> (try_to_wake_up+0x94/0x140 <c0110474>) (T1/#3) <...> 32105 0 3 00000003 00000003 [0011939614228436] 0.000ms (+0.000ms): preempt_schedule+0x11/0x80 <c02b57c1> (try_to_wake_up+0x94/0x140 <c0110474>) (T3/#4) <...>-32105 0dn.3 0�s : try_to_wake_up+0x11e/0x140 <c01104fe> <<...>-2> (69 76): (T1/#5) <...> 32105 0 3 00000002 00000005 [0011939614228942] 0.000ms (+0.000ms): preempt_schedule+0x11/0x80 <c02b57c1> (try_to_wake_up+0xf8/0x140 <c01104d8>) (T1/#6) <...> 32105 0 3 00000002 00000006 [0011939614229130] 0.000ms (+0.000ms): wake_up_process+0x35/0x40 <c0110555> (do_softirq +0x3f/0x50 <c011b05f>) (T6/#7) <...>-32105 0dn.1 1�s < (1) (T1/#8) <...> 32105 0 2 00000001 00000008 [0011939614229782] 0.001ms (+0.000ms): radix_tree_gang_lookup+0xe/0x70 <c01e05ee> (nfs_wait_on_requests+0x6d/0x110 <c01c744d>) (T1/#9) <...> 32105 0 2 00000001 00000009 [0011939614229985] 0.001ms (+0.000ms): __lookup+0xe/0xd0 <c01e051e> (radix_tree_gang_lookup +0x52/0x70 <c01e0632>) (T1/#10) <...> 32105 0 2 00000001 0000000a [0011939614230480] 0.001ms (+0.000ms): radix_tree_gang_lookup+0xe/0x70 <c01e05ee> (nfs_wait_on_requests+0x6d/0x110 <c01c744d>) (T1/#11) <...> 32105 0 2 00000001 0000000b [0011939614230634] 0.002ms (+0.000ms): __lookup+0xe/0xd0 <c01e051e> (radix_tree_gang_lookup +0x52/0x70 <c01e0632>) (T1/#12) <...> 32105 0 2 00000001 0000000c [0011939614230889] 0.002ms (+0.000ms): radix_tree_gang_lookup+0xe/0x70 <c01e05ee> (nfs_wait_on_requests+0x6d/0x110 <c01c744d>) (T1/#13) <...> 32105 0 2 00000001 0000000d [0011939614231034] 0.002ms (+0.000ms): __lookup+0xe/0xd0 <c01e051e> (radix_tree_gang_lookup +0x52/0x70 <c01e0632>) (T1/#14) <...> 32105 0 2 00000001 0000000e [0011939614231302] 0.002ms (+0.000ms): radix_tree_gang_lookup+0xe/0x70 <c01e05ee> (nfs_wait_on_requests+0x6d/0x110 <c01c744d>) (T1/#15) <...> 32105 0 2 00000001 0000000f [0011939614231419] 0.002ms (+0.000ms): __lookup+0xe/0xd0 <c01e051e> (radix_tree_gang_lookup +0x52/0x70 <c01e0632>)
(last two lines just repeat)
> Cheers, > Trond
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