Messages in this thread | | | Subject | Re: [patch v3 3/3] percpu_counter: use atomic64 for counter in SMP | From | Shaohua Li <> | Date | Mon, 18 Apr 2011 15:43:45 +0800 |
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On Fri, 2011-04-15 at 12:15 +0800, Tejun Heo wrote: > Hello, > > On Thu, Apr 14, 2011 at 10:04:50AM +0800, shaohua.li@intel.com wrote: > > Index: linux/lib/percpu_counter.c > > =================================================================== > > --- linux.orig/lib/percpu_counter.c 2011-04-14 09:53:04.000000000 +0800 > > +++ linux/lib/percpu_counter.c 2011-04-14 10:01:29.000000000 +0800 > > @@ -59,13 +59,17 @@ void percpu_counter_set(struct percpu_co > > { > > int cpu; > > > > - spin_lock(&fbc->lock); > > + /* > > + * Don't really need to disable preempt here, just make sure there is > > + * no big latency because of preemption > > + */ > > + preempt_disable(); > > for_each_possible_cpu(cpu) { > > s32 *pcount = per_cpu_ptr(fbc->counters, cpu); > > *pcount = 0; > > } > > - fbc->count = amount; > > - spin_unlock(&fbc->lock); > > + atomic64_set(&fbc->count, amount); > > + preempt_enable(); > > Disabling preemption here doesn't make any sense. > percpu_counter_set() inherently requires its users to guarantee that > no other user is modifying the percpu counter. ha, ok. should I still rebase the patch against Christoph's patch? Looks that one is still not settled down.
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