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

From: Jens Axboe
Date: Fri Mar 25 2016 - 10:08:32 EST

On 03/25/2016 01:32 AM, Baolin Wang wrote:
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.

But more than half of the trace points you added, those are DIRECTLY related to the block event. So what you are saying makes little sense. I see you resend it with the same trace points, I'll comment on that mail.

Jens Axboe