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

[Stephen Bates]

On 2017-04-05, 7:14 PM, "Jens Axboe" <ax...@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);

and then bin any IO over 64K in the largest of the two buckets based on 
direction. I’ll implement this in a v3….

Cheers

Stephen