[PATCH v2 2/2] blk-mq: Add a polling specific stats function

[Jens Axboe]

On 04/07/2017 06:11 AM, Stephen  Bates wrote:
> On 2017-04-05, 7:14 PM, "Jens Axboe" <axboe at kernel.dk> wrote:
> 
>> Why not just have 8 buckets, and make it:
>>
>> 	bucket = ddir + ilog2(bytes) - 9;
>>
>> and cap it at MAX_BUCKET (8) and put all those above into the top
>> bucket.
> 
> Thanks. However, that equation does not differentiate between
> direction and size. Instead we can use
> 
> bucket = ddir + 2*(ilog2(bytes) - 9);

It would be cleaner to just embed the fact that we have 2 sets of
identical buckets, and return 

	bucket = ilog2(bytes) - 9;

and have poll_stat be indexed by:

	->poll_stat[ddir][bucket];

instead.

-- 
Jens Axboe