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SubjectRe: [patch] HT scheduler, sched-2.5.59-F3
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On Fri, 2003-02-07 at 00:38, Ingo Molnar wrote:
>
> the attached patch is against current BK. I tested it on the following 6
> kernel/hardware combinations:
>
> (HT SMP kernel, SMP kernel, UP kernel) X (non-HT SMP box, HT SMP box)
>
> all kernels compiled & booted fine.
>
> Ingo
>
Tested on a 4 node (16 700 MHZ P3 processors, 16 GB memory) NUMAQ.
Works fine. Ran kernbench and schedbench (aka numatest) on this.
Also tested the E6 variant of this patch. Both show similar results
as on stock kernels, except for light loads where the stock kernel
tends to spread processes more evenly across nodes.

On Tue, 2003-02-04 at 10:48, Erich Focht suggested the following to
address this light load case:
> > +#define CAN_MIGRATE_TASK(p,rq,cpu) \
> > + (((idle && AGRESSIVE_IDLE_STEAL) || \
> > + (jiffies - (p)->last_run > cache_decay_ticks)) && \
> > + !task_running(p) && task_allowed(p, cpu))
>
> this is still either all or nothing. I like the idle rebalancing
> beeing more aggressive than the non-idle one, but it could be
> smoother. What speaks against the following?
>
> > +#define CAN_MIGRATE_TASK(p,rq,cpu) \
> > + ((jiffies - (p)->last_run > (cache_decay_ticks >> idle)) && \
> > + !task_running(p) && task_allowed(p, cpu))
>
>
> Where it hurts? As Andrew mentioned, Michael has seen weird behavior
> with the D7..E6(AGRESSIVE_IDLE_STEAL=1) alike schedulers.

My testing did not show any noticeable difference with Erich's change.

Results below include the following kernels:

ingoF3 = linux 2.5.59 + Ingo's F3 patch + cputime_stats patch
ingoE6-59 = linux 2.5.59 + Ingo's E6 patch + cputime_stats patch
ingoE6-erich-59 = ingoE6-59 with change suggested by Erich Focht
stock59 = linux 2.5.59 + cputime_stats patch

Kernbench:
Elapsed User System CPU
ingoF3 27.97s 275.96s 71.916s 1243.6%
ingoE6-59 27.826s 276.514s 71.542s 1250.4%
ingoE6-erich-59 27.59s 276.028s 69.964s 1254.2%
stock59 27.58s 275.92s 71.134s 1258.4%

Schedbench 4:
AvgUser Elapsed TotalUser TotalSys
ingoF3 33.64 41.43 134.61 0.71
ingoE6-59 33.21 44.76 132.88 0.70
ingoE6-erich-59 33.49 43.80 134.02 0.81
stock59 22.62 37.16 90.50 0.82

Schedbench 8:
AvgUser Elapsed TotalUser TotalSys
ingoF3 35.86 53.73 286.97 1.93
ingoE6-59 32.65 44.14 261.25 1.52
ingoE6-erich-59 35.83 68.42 286.69 1.90
stock59 29.26 42.79 234.18 1.62

Schedbench 16:
AvgUser Elapsed TotalUser TotalSys
ingoF3 52.66 56.65 842.81 4.09
ingoE6-59 52.94 56.69 847.25 3.57
ingoE6-erich-59 52.90 58.27 846.57 3.93
stock59 52.91 57.08 846.75 3.58

Schedbench 32:
AvgUser Elapsed TotalUser TotalSys
ingoF3 56.42 115.94 1805.65 6.31
ingoE6-59 56.62 116.70 1812.17 6.76
ingoE6-erich-59 56.45 117.27 1806.68 6.17
stock59 56.66 117.14 1813.41 6.15

Schedbench 64:
AvgUser Elapsed TotalUser TotalSys
ingoF3 56.52 231.19 3617.94 14.84
ingoE6-59 56.93 237.63 3644.36 16.78
ingoE6-erich-59 56.98 236.96 3647.06 15.64
stock59 56.56 230.71 3620.70 15.94

--

Michael Hohnbaum 503-578-5486
hohnbaum@us.ibm.com T/L 775-5486

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