Messages in this thread | | | Date | Wed, 3 Jun 2020 15:35:28 +0200 | From | Michal Hocko <> | Subject | Re: [PATCH v4 2/4] mm/util.c: make vm_memory_committed() more accurate |
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On Fri 29-05-20 09:06:08, Feng Tang wrote: > percpu_counter_sum_positive() will provide more accurate info. > > As with percpu_counter_read_positive(), in worst case the deviation > could be 'batch * nr_cpus', which is totalram_pages/256 for now, > and will be more when the batch gets enlarged. > > Its time cost is about 800 nanoseconds on a 2C/4T platform and > 2~3 microseconds on a 2S/36C/72T server in normal case, and in > worst case where vm_committed_as's spinlock is under severe > contention, it costs 30~40 microseconds for the 2S/36C/72T sever, > which should be fine for its only two users: /proc/meminfo and > HyperV balloon driver's status trace per second. > > Signed-off-by: Feng Tang <feng.tang@intel.com>
I cannot speak for HyperV part. Cc maintainers but this shouldn't be a problem for meminfo.
Acked-by: Michal Hocko <mhocko@suse.com>
> --- > mm/util.c | 2 +- > 1 file changed, 1 insertion(+), 1 deletion(-) > > diff --git a/mm/util.c b/mm/util.c > index 9b3be03..3c7a08c 100644 > --- a/mm/util.c > +++ b/mm/util.c > @@ -790,7 +790,7 @@ struct percpu_counter vm_committed_as ____cacheline_aligned_in_smp; > */ > unsigned long vm_memory_committed(void) > { > - return percpu_counter_read_positive(&vm_committed_as); > + return percpu_counter_sum_positive(&vm_committed_as); > } > EXPORT_SYMBOL_GPL(vm_memory_committed); > > -- > 2.7.4 >
-- Michal Hocko SUSE Labs
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