lkml.org 
[lkml]   [2017]   [Nov]   [24]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
/
SubjectRe: i8k_smm_func() takes enormous of time to execute
From
Date
Hi Oleksandr,

On jeu., 2017-11-23 at 22:41 +0100, Oleksandr Natalenko wrote:
> I've noticed that querying Dell Vostro 3360 hwmon sensor freezes the system
> completely (like, really completely, even mouse cursor does not move, and
> sound playback stops) for approx. half of a second. Then, system recovers and
> runs as usual. Also, sensor readings are okay, for instance:
>
> ===
> $ sensors dell_smm-virtual-0
> dell_smm-virtual-0
> Adapter: Virtual device
> Processor Fan: 5615 RPM
> CPU: +51.0°C
> Ambient: +36.0°C
> Other: +63.0°C
> SODIMM: +41.0°C
> ===
>
> So, I've used trace-cmd to check what takes that much amount of time to
> execute, and got this:
>
> ===
> # trace-cmd record -p function_graph -l i8k_smm -F sensors dell_smm-virtual-0
> $ trace-cmd report
> ...
> sensors-23694 [002] 89099.214369: funcgraph_entry: # 503440.746 us |
> i8k_smm();
> ...
> ===
>
> Clearly, 0.5 s delay.
>
> Looking at i8k_smm(), it calls i8k_smm_func() on 0th CPU:
>
> ===
> 232 ret = smp_call_on_cpu(0, i8k_smm_func, regs, true);
> ===
>
> which, in turn, does some asm magic.
>
> I know that SMM is kinda "black box", and kernel has little to do with it, but
> I think that under Windows, for instance, it would work without freezes. So,
> likely, querying SMM might be done differently.
>
> I do not know how to approach this issue, thus asking for help/advice. Also,
> CCing Jonathan since the comment before asm magic says this:
>
> ===
> 137 * Call the System Management Mode BIOS. Code provided by Jonathan
> Buzzard.
> ===
>
> This was also reported in various places before, for instance, [1], but
> unfortunately, without any solution.

There are two patches waiting to be tested in
https://bugzilla.kernel.org/show_bug.cgi?id=195751

--
Jean Delvare
SUSE L3 Support

\
 
 \ /
  Last update: 2017-11-24 11:23    [W:0.053 / U:2.408 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site