On Mon, 9 May 2005 21:24, Markus Törnqvist wrote:
> I beg to differ with Mr. Carvalho's assesment with this patch;
> it works like a charm, and then some.
>
> The rest of the message is just my analysis of the situation
> ran on a Dell PowerEdge 2850, dual hyperthread Xeon EM64Ts, with
> Debian Pure64 Sarge installed.
Thanks for feedback.
> PID USER PR NI VIRT SHR S %CPU %MEM TIME+ #C COMMAND
> 3917 mjt 26 0 5660 936 R 99.9 0.0 3:37.61 0 load_base.sh
> 3918 mjt 25 0 5660 936 R 99.9 0.0 3:37.60 3 load_base.sh
> 3916 mjt 26 0 5660 936 R 52.7 0.0 2:02.37 2 load_base.sh
> 3919 mjt 39 19 5660 936 R 7.0 0.0 0:13.80 1 load_base.sh
> 3920 mjt 39 19 5660 936 R 3.0 0.0 0:06.05 2 load_base.sh
>
> top - 11:09:24 up 15:30, 2 users, load average: 4.99, 3.55, 1.63
> PID USER PR NI VIRT SHR S %CPU %MEM TIME+ #C COMMAND
> 3917 mjt 25 0 5660 936 R 99.6 0.0 6:11.35 0 load_base.sh
> 3918 mjt 24 0 5660 936 R 99.6 0.0 6:11.34 3 load_base.sh
> 3916 mjt 39 0 5660 936 R 65.7 0.0 3:28.95 2 load_base.sh
> 3919 mjt 39 19 5660 936 R 7.0 0.0 0:23.54 1 load_base.sh
> 3920 mjt 39 19 5660 936 R 3.0 0.0 0:10.33 2 load_base.sh
These runs don't look absolutely "ideal" as one nice 19 task is bound to cpu1
however since you're running hyperthreading it would seem the SMT nice code
is keeping that under check anyway (0:23 vs 6:11)
> top - 11:12:32 up 15:33, 2 users, load average: 4.99, 4.22, 2.24
> PID USER PR NI VIRT RES SHR S %CPU %MEM TIME+ #C COMMAND
> 3917 mjt 35 0 5660 1136 936 R 99.9 0.0 9:28.56 0
> load_base.sh 3918 mjt 34 0 5660 1136 936 R 99.5 0.0 9:28.54 3
> load_base.sh 3916 mjt 35 0 5660 1136 936 R 61.7 0.0 5:19.77 2
> load_base.sh 3919 mjt 39 19 5660 1136 936 R 6.0 0.0 0:36.07 1
> load_base.sh 3920 mjt 39 19 5660 1136 936 R 3.0 0.0 0:15.82 2
> load_base.sh
>
> $ ./load.sh 7
> top - 11:13:49 up 15:35, 2 users, load average: 5.17, 4.40, 2.45
> PID USER PR NI VIRT RES SHR S %CPU %MEM TIME+ #C COMMAND
> 3952 mjt 29 0 5660 1140 936 R 99.9 0.0 0:33.53 2
> load_base.sh 3950 mjt 31 0 5660 1140 936 R 99.5 0.0 0:33.33 1
> load_base.sh 3953 mjt 30 0 5660 1140 936 R 55.7 0.0 0:16.82 3
> load_base.sh 3951 mjt 39 0 5660 1140 936 R 43.8 0.0 0:16.70 3
> load_base.sh 3949 mjt 39 0 5660 1140 936 R 23.9 0.0 0:13.18 0
> load_base.sh 3954 mjt 39 19 5660 1140 936 R 2.0 0.0 0:00.64 0
> load_base.sh 3955 mjt 39 19 5660 1140 936 R 2.0 0.0 0:00.64 0
> load_base.sh
>
> top - 11:14:53 up 15:36, 2 users, load average: 6.38, 4.91, 2.76
> PID USER PR NI VIRT RES SHR S %CPU %MEM TIME+ #C COMMAND
> 3950 mjt 23 0 5660 1140 936 R 99.9 0.0 1:39.67 1
> load_base.sh 3952 mjt 21 0 5660 1140 936 R 99.9 0.0 1:39.87 2
> load_base.sh 3951 mjt 39 0 5660 1140 936 R 52.7 0.0 0:49.91 3
> load_base.sh 3953 mjt 22 0 5660 1140 936 R 47.8 0.0 0:49.95 3
> load_base.sh 3949 mjt 39 0 5660 1140 936 R 43.8 0.0 0:38.70 0
> load_base.sh 3954 mjt 39 19 5660 1140 936 R 2.0 0.0 0:01.90 0
> load_base.sh 3955 mjt 39 19 5660 1140 936 R 2.0 0.0 0:01.90 0
These runs pretty much confirm what I found to happen. My test machine for
this was also 4x. I can't see how the code would behave differently on 2x.
Perhaps if I make the prio_bias multiplied instead of added to the cpu load
it will be less affected by SCHED_LOAD_SCALE. The attached patch was
confirmed during testing to also provide smp distribution according to nice
on 4x. Carlos I know your machine is in production so you testing may not be
easy for you. Please try this on top if you have time.
Cheers,
Con
---
This patch alters the effect priority bias has on busy rebalancing by
multiplying the cpu load by the total priority instead of adding it.
Signed-off-by: Con Kolivas <[email protected]>
Index: linux-2.6.11-smpnice/kernel/sched.c
===================================================================
--- linux-2.6.11-smpnice.orig/kernel/sched.c 2005-05-07 23:25:15.000000000 +1000
+++ linux-2.6.11-smpnice/kernel/sched.c 2005-05-09 21:42:02.000000000 +1000
@@ -953,8 +953,8 @@ static inline unsigned long source_load(
* If we are balancing busy runqueues the load is biased by
* priority to create 'nice' support across cpus.
*/
- cpu_load += rq->prio_bias;
- load_now += rq->prio_bias;
+ cpu_load *= rq->prio_bias;
+ load_now *= rq->prio_bias;
}
return min(cpu_load, load_now);
}
@@ -969,8 +969,8 @@ static inline unsigned long target_load(
load_now = rq->nr_running * SCHED_LOAD_SCALE;
if (idle == NOT_IDLE) {
- cpu_load += rq->prio_bias;
- load_now += rq->prio_bias;
+ cpu_load *= rq->prio_bias;
+ load_now *= rq->prio_bias;
}
return max(cpu_load, load_now);
}
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