Re: [PATCH v2 5/5] mm/compaction: add tracepoint to observe behaviour of compaction defer

Vlastimil Babka
2015-01-13T08:35:31Z

On 01/13/2015 08:18 AM, Joonsoo Kim wrote:
> On Mon, Jan 12, 2015 at 05:35:47PM +0100, Vlastimil Babka wrote:
>> Hm what if we avoided dirtying the cache line in the non-deferred case? Would be
>> simpler, too?
>>
>> if (zone->compact_considered + 1 >= defer_limit)
>> return false;
>>
>> zone->compact_considered++;
>>
>> trace_mm_compaction_defer_compaction(zone, order);
>>
>> return true;
>
> Okay. I will include this minor optimization in next version of this
> patch.

Hm, on second thought, the "+ 1" part would break compaction_restarting() and
it's ugly anyway. Removing "+ 1" would increase the number of
compaction_deferred() attempts until success by one. Which should be negligible,
but maybe not good to hide it in a tracepoint patch. Sorry for the noise.

> Thanks.
>