linux-kernel - Re: thousands of kworker processes with 4.7.x and 4.8-rc*

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Message-ID: <95eb1349-fcd4-4713-31fc-695c6255ae30@gmail.com>
Date:   Sun, 25 Sep 2016 22:07:52 +0300
From:   Nikolay Borisov <n.borisov.lkml@...il.com>
To:     Tomasz Chmielewski <mangoo@...g.org>,
        Mike Galbraith <umgwanakikbuti@...il.com>
Cc:     LKML <linux-kernel@...r.kernel.org>
Subject: Re: thousands of kworker processes with 4.7.x and 4.8-rc*



On 25.09.2016 15:40, Tomasz Chmielewski wrote:
> On 2016-09-25 18:29, Tomasz Chmielewski wrote:
> 
>>> I'll try to bisect.
>>
>> OK, not a kernel regression, but some config change caused it.
>> However, I'm not able to locate which change exactly.
>>
>> I'm attaching two configs which I've tried with 4.7.3 - one results in
>> thousands of kworkers, and the other doesn't. Also included a diff
>> between them.
>>
>> Any obvious changes I should try?
> 
> The problem is the allocator.
> 
> -CONFIG_SLUB=y
> +CONFIG_SLAB=y
> 
> 
> With SLUB, I'm getting a handful of kworker processes, as expected.
> 
> With SLAB, I'm getting thousands of kworker processes.
> 
> 
> Not sure if that's expected behaviour or not.


Why don't you sample the stacks of some of those kworker processes to
see if they are all executing a parituclar piece of work. That might
help you narrow down where they originate from. Cat multiple
/proc/$kworker-pid/stack files and see if a pattern emerges.

Regards,
Nikolay

> 
> 
> Tomasz Chmielewski
> https://lxadm.com
> 
>