Re: [PATCH] mmc: Provide tracepoints for request processing

From: Baolin Wang
Date: Fri Mar 25 2016 - 03:32:29 EST

On 24 March 2016 at 22:08, Jens Axboe <axboe@xxxxxx> wrote:
> On 03/24/2016 05:54 AM, Baolin Wang wrote:
>> This patch provides some tracepoints for the lifecycle of a request from
>> fetching to completion to help with performance analysis of MMC subsystem.
> Most of these already exist as block layer trace points, why do we need mmc
> specific ones?

Currently the MMC core does not have any tracepoints for use with
ftrace. These are very useful as they provide a very low overhead
runtime controllable way of getting diagnostics from the system which
is capable of recording a great deal of information without impacting
system performance. We have tracepoints in the block layer so we can
do some trace of MMC but none in MMC itself so adding some where
appropriate would help people follow the activity of subsystem.

> --
> Jens Axboe

Best Regards