Messages in this thread | | | Date | Sat, 28 Feb 2009 18:37:08 +0900 (JST) | Subject | Re: [PATCH] change cpuacct usage percpu format v2 | From | "KAMEZAWA Hiroyuki" <> |
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Dhaval Giani wrote: > On Sat, Feb 28, 2009 at 02:25:22PM +0900, KAMEZAWA Hiroyuki wrote: >> Dhaval Giani wrote: >> > On Sat, Feb 28, 2009 at 09:42:17AM +0900, KAMEZAWA Hiroyuki wrote: >> >> KAMEZAWA Hiroyuki wrote: >> >> BTW, current interface to reset cpuacct (write ops) just reset >> >> specified level of cpuacct and will not clear other hierarchical >> levels. >> >> Doesn't this behavior confuse software ? >> >> >> > >> > hmmm. This got missed when we introduced hierarchy. But I wonder if it >> > is needed? >> > >> IIUC, cpuacct.usage just shows sum of itself and all children's usage >> and >> its own usage can be calclated by reading all usage of hierarchy. >> So, reset ops seems to be a bit broken. >> And by this, parent's usage can be smaller than children. >> > > Actually now that I think about it, it does make sense, but when I > started implementing it, a question popped up, if we reset a child's > counter, then the parent is going to have a much greater usage than the > sum of the children. I wonder if this behavior is fine? > As far as the user remembers he did reset...
>> How about adding limitation as "you can clear usage only when there are >> no >> children" ? Maybe not very strange limitaton under hierarchical system. >> > > Just the question I asked. Beyond that I don't think we should have such a > limitation on reset. > Ok, I don't have strong requirements. I'll recomend users that you should reset all children(hierarchy) at the same time.
Maybe no problem if we have private-usage counter....but it means one more percpu array...
Thanks, -Kame
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