lkml.org 
[lkml]   [2018]   [Apr]   [23]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
/
SubjectRe: [PATCH] ALSA: hda: Request driver probe from an async task
From
Date
Dear Takashi,


On 04/23/18 14:21, Takashi Iwai wrote:
> On Mon, 23 Apr 2018 14:05:52 +0200,
> Paul Menzel wrote:
>>
>> From: Paul Menzel <pmenzel@molgen.mpg.de>
>> Date: Sat, 24 Mar 2018 09:28:43 +0100
>>
>> On an ASRock E350M1, with Linux 4.17-rc1 according to `initcall_debug`
>> calling `azx_driver_init` takes sometimes more than a few milliseconds,
>> and up to 200 ms.
>>
>> ```
>> [ 2.892598] calling azx_driver_init+0x0/0xfe4 [snd_hda_intel] @ 218
>> [ 2.943002] initcall azx_driver_init+0x0/0xfe4 [snd_hda_intel]
>> returned 0 after 49195 usecs
>> ```
>>
>> Trying to execute the Linux kernel in less than 500 ms, this is quite a
>> hold-up, and therefore request the probe from an async task.
>>
>> With this change, the test shows, that the function returns earlier.
>>
>> ```
>> [ 3.254800] calling azx_driver_init+0x0/0xfe4 [snd_hda_intel] @ 227
>> [ 3.254887] initcall azx_driver_init+0x0/0xfe4 [snd_hda_intel]
>> returned 0 after 66 usecs
>> ```
>>
>> The same behavior is visible on a Dell OptiPlex 7010. The longer times
>> seem to happen, when the module *e1000e* is probed during the same time.
>>
>> Signed-off-by: Paul Menzel <pmenzel@molgen.mpg.de>
>
> What actually took so long? Could you analyze further instead of
> blindly putting the flag?

Well, I am not sure. Could you please give me hints, how to debug this
further? Is there some debug flag?

I am only aware of the Ftrace framework, but in my experience it also
skews the timings quite a bit, so might not be the best choice.


Kind regards,

Paul

[unhandled content-type:application/pkcs7-signature]
\
 
 \ /
  Last update: 2018-04-23 14:31    [W:0.155 / U:0.116 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site