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Date: Sun, 6 Apr 2008 02:29:14 +0530 From: Dhaval Giani <dhaval@...ux.vnet.ibm.com> To: Balaji Rao <balajirrao@...il.com> Cc: linux-kernel@...r.kernel.org, containers@...ts.osdl.org, menage@...gle.com, a.p.zijlstra@...llo.nl, balbir@...ibm.com, Srivatsa Vaddagiri <vatsa@...ux.vnet.ibm.com> Subject: Re: [RFC][-mm] [1/2] Simple stats for cpu resource controller On Sun, Apr 06, 2008 at 02:01:52AM +0530, Balaji Rao wrote: > On Sunday 06 April 2008 01:10:41 am Dhaval Giani wrote: > > > +}; > > > + > > > +struct cpu_cgroup_stat_cpu { > > > + s64 count[CPU_CGROUP_STAT_NSTATS]; > > > > u64? time does not go negative :) > Right. But these stats are not only going to measure time. We need the same > variables for measuring other stats as well. I'm not sure if we would > encounter scheduler stats that would count negative. > > Balbir, what do you say ? I would prefer to keep the stats logically separate. So something like struct cpu_cgroup_stat_cpu { u64 time[]; s64 some_other_stat; } and so on. (I am not sure, is there some advantage gained by using structs?) Makes the code more maintainable imho. > > > count also is not very clear? Can you give a more descriptive name? > > > ok. How does 'value' look ? > > <snip> > > > > +static s64 cpu_cgroup_read_stat(struct cpu_cgroup_stat *stat, > > > + enum cpu_cgroup_stat_index idx) > > > +{ > > > + int cpu; > > > + s64 ret = 0; > > > + unsigned long flags; > > > > > + > > > + local_irq_save(flags); > > > > I am just wondering. Is local_irq_save() enough? > > > Hmmm.. You are right.This does not prevent concurrent updates on other CPUs > from crossing a 32bit boundary. Am not sure how to do this in a safe way. I > can only think of using atomic64_t now.. > I am going to answer that one when I am awake :-) -- regards, Dhaval -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@...r.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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