On Sat, 2005-03-19 at 20:16 +0100, Ingo Molnar wrote:
> i have released the -V0.7.41-00 Real-Time Preemption patch (merged to
> 2.6.12-rc1), which can be downloaded from the usual place:
>
> http://redhat.com/~mingo/realtime-preempt/
>
3ms latency in the NFS client code. Workload was a kernel compile over
NFS.
preemption latency trace v1.1.4 on 2.6.12-rc1-RT-V0.7.41-00
--------------------------------------------------------------------
latency: 3178 ïs, #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 0ïs : 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 1ïs < (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)
This is probably not be a regression; I had never tested this with NFS
before.
Lee
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