Messages in this thread | | | Date | Wed, 30 Sep 2015 15:22:52 -0700 (PDT) | From | David Rientjes <> | Subject | Re: [PATCH 03/10] mm, page_alloc: Remove unnecessary taking of a seqlock when cpusets are disabled |
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On Mon, 21 Sep 2015, Mel Gorman wrote:
> There is a seqcounter that protects against spurious allocation failures > when a task is changing the allowed nodes in a cpuset. There is no need > to check the seqcounter until a cpuset exists. > > Signed-off-by: Mel Gorman <mgorman@techsingularity.net> > Acked-by: Christoph Lameter <cl@linux.com> > Acked-by: David Rientjes <rientjes@google.com> > Acked-by: Vlastimil Babka <vbabka@suse.cz> > Acked-by: Michal Hocko <mhocko@suse.com> > --- > include/linux/cpuset.h | 6 ++++++ > 1 file changed, 6 insertions(+) > > diff --git a/include/linux/cpuset.h b/include/linux/cpuset.h > index 1b357997cac5..6eb27cb480b7 100644 > --- a/include/linux/cpuset.h > +++ b/include/linux/cpuset.h > @@ -104,6 +104,9 @@ extern void cpuset_print_task_mems_allowed(struct task_struct *p); > */ > static inline unsigned int read_mems_allowed_begin(void) > { > + if (!cpusets_enabled()) > + return 0; > + > return read_seqcount_begin(¤t->mems_allowed_seq); > } > > @@ -115,6 +118,9 @@ static inline unsigned int read_mems_allowed_begin(void) > */ > static inline bool read_mems_allowed_retry(unsigned int seq) > { > + if (!cpusets_enabled()) > + return false; > + > return read_seqcount_retry(¤t->mems_allowed_seq, seq); > } >
I thought this was going to test nr_cpusets() <= 1?
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