linux-kernel - Re: [Query] Preemption (hogging) of the work handler

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Message-ID: <20160712130231.GM4695@ubuntu>
Date:	Tue, 12 Jul 2016 06:02:31 -0700
From:	Viresh Kumar <viresh.kumar@...aro.org>
To:	"Rafael J. Wysocki" <rjw@...ysocki.net>
Cc:	Jan Kara <jack@...e.cz>,
	Sergey Senozhatsky <sergey.senozhatsky@...il.com>,
	Tejun Heo <tj@...nel.org>,
	Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
	Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
	vlevenetz@...sol.com, vaibhav.hiremath@...aro.org,
	alex.elder@...aro.org, johan@...nel.org, akpm@...ux-foundation.org,
	rostedt@...dmis.org,
	Sergey Senozhatsky <sergey.senozhatsky.work@...il.com>,
	Linux PM list <linux-pm@...r.kernel.org>
Subject: Re: [Query] Preemption (hogging) of the work handler

On 12-07-16, 14:24, Rafael J. Wysocki wrote:
> On Monday, July 11, 2016 03:46:01 PM Viresh Kumar wrote:
> > Yeah and I am not sure how should I go ahead about this issue now :)
> 
> FWIW, I think the reason why the "synchronous printk" works is because after
> disabling the non-boot CPU, the only remaining one disables local interrupts
> and won't do any async work any more until resume.

Right. After disabling interrupts, the other printk messages gets
printed only after the system resumes. I am not that worried about
printk not working after that point, but on how does asynchronous
printing affect the system to crash or come to a complete hang?

Any clues on why that can happen ?

> But you started to talk about suspend/resume and such at one point and that
> message should have been CCed to linux-pm.
> 
> And the reason why is because problems you see during suspend/resume may very
> well be suspend-specific and not visible otherwise.  In which case you'll
> likely need input from the people on linux-pm.

Yeah, I *should* have cc'd the PM list then. Thanks for helping out
Rafael :)

-- 
viresh