Re: [PATCH] hugeltb: Mark hugelb_max_hstate __read_mostly

["Aneesh Kumar K.V" <aneesh.kumar@linux.vnet.ibm.com>]

Christoph Lameter <cl@linux.com> writes:

> On Thu, 14 Jun 2012, Michal Hocko wrote:
>
>> On Thu 14-06-12 19:26:18, Aneesh Kumar K.V wrote:
>> > From: "Aneesh Kumar K.V" <aneesh.kumar@linux.vnet.ibm.com>
>> >
>> > Signed-off-by: Aneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com>
>> > ---
>> >  include/linux/hugetlb.h |    2 +-
>> >  mm/hugetlb.c            |    2 +-
>> >  2 files changed, 2 insertions(+), 2 deletions(-)
>> >
>> > diff --git a/include/linux/hugetlb.h b/include/linux/hugetlb.h
>> > index 9650bb1..0f0877e 100644
>> > --- a/include/linux/hugetlb.h
>> > +++ b/include/linux/hugetlb.h
>> > @@ -23,7 +23,7 @@ struct hugepage_subpool {
>> >  };
>> >
>> >  extern spinlock_t hugetlb_lock;
>> > -extern int hugetlb_max_hstate;
>> > +extern int hugetlb_max_hstate __read_mostly;
>>
>> It should be used only for definition
>
> And a rationale needs to be given. Since this patch had no effect, I would
> think that the patch is just the expression of the belief of the patcher
> that something would improve performancewise.
>
> But there seems to no need for this patch otherwise someone would have
> verified that the patch has the intended beneficial effect on performance.
>

The variable is never modified after boot.

-aneesh

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