Messages in this thread | | | From | KOSAKI Motohiro <> | Subject | Re: [PATCH 1/3 v2] softirq: Introduce statistics for softirq | Date | Wed, 26 Nov 2008 19:14:58 +0900 (JST) |
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> On Sat, 22 Nov 2008 14:36:34 +0900 (JST) > KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com> wrote: > > > > Statistics for softirq doesn't exist. > > > It will be helpful like statistics for interrupts. > > > This patch introduces counting the number of softirq, > > > which will be exported in /proc/softirqs. > > > > > > When softirq handler consumes much CPU time, > > > /proc/stat is like the following. > > > > > > $ while :; do cat /proc/stat | head -n1 ; sleep 10 ; done > > > cpu 88 0 408 739665 583 28 2 0 0 > > > cpu 450 0 1090 740970 594 28 1294 0 0 > > > ^^^^ > > > softirq > > > > > > In such a situation, > > > /proc/softirqs shows us which softirq handler is invoked. > > > We can see the increase rate of softirqs. > > > > > > <before> > > > $ cat /proc/softirqs > > > CPU0 CPU1 CPU2 CPU3 > > > HI 0 0 0 0 > > > TIMER 462850 462805 462782 462718 > > > NET_TX 0 0 0 365 > > > NET_RX 2472 2 2 40 > > > BLOCK 0 0 381 1164 > > > TASKLET 0 0 0 224 > > > SCHED 462654 462689 462698 462427 > > > RCU 3046 2423 3367 3173 > > > > > > <after> > > > $ cat /proc/softirqs > > > CPU0 CPU1 CPU2 CPU3 > > > HI 0 0 0 0 > > > TIMER 463361 465077 465056 464991 > > > NET_TX 53 0 1 365 > > > NET_RX 3757 2 2 40 > > > BLOCK 0 0 398 1170 > > > TASKLET 0 0 0 224 > > > SCHED 463074 464318 464612 463330 > > > RCU 3505 2948 3947 3673 > > > > Maybe, this printing format don't works well on >100 CPUS. > > > > Do you have any experience of trouble-shooting by this patch? > > Actually, I don't understand this patch usuful working situation. > > When reported that CPU TIME of softirq went up, > we had to investigate the cause. > In that case, kind of network looked suspicious. > We added such a function to confirm. > > Original patch shows ticks of softirqs. > But /proc/interrups have counts of interrupts. > So we changed from ticks to counts.
ok. it seems reasonable reason. and this patch looks good to me.
Reviewed-by: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
> > > Honestly, I think HI and TASKLET are not beneficialness. > > end user can't know what tasklet spent time. > > TIMER also are not so much useful because it always have the same rate. > > > > So.. guessing... > > > > ultra band-width networking problem?
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