linux-kernel - Re: [PATCH v1] PM: sleep: Restore asynchronous device resume optimization

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Message-ID: <2f125955-8c7c-465c-938c-8768f7ca360b@samsung.com>
Date: Wed, 7 Feb 2024 19:55:51 +0100
From: Marek Szyprowski <m.szyprowski@...sung.com>
To: Tejun Heo <tj@...nel.org>, "Rafael J. Wysocki" <rafael@...nel.org>
Cc: "Rafael J. Wysocki" <rjw@...ysocki.net>, Linux PM
	<linux-pm@...r.kernel.org>, Ulf Hansson <ulf.hansson@...aro.org>, Nathan
	Chancellor <nathan@...nel.org>, LKML <linux-kernel@...r.kernel.org>,
	Stanislaw Gruszka <stanislaw.gruszka@...ux.intel.com>, Lai Jiangshan
	<jiangshanlai@...il.com>, Naohiro.Aota@....com, kernel-team@...a.com
Subject: Re: [PATCH v1] PM: sleep: Restore asynchronous device resume
 optimization

On 07.02.2024 17:39, Tejun Heo wrote:
> On Wed, Feb 07, 2024 at 12:25:46PM +0100, Rafael J. Wysocki wrote:
>> The other one is that what happens during async resume does not meet
>> the assumptions of commit 5797b1c18919 (for example, it can easily
>> produce a chain of interdependent work items longer than 8) and so it
>> breaks things.
> Ah, that's fascinating. But aren't CPUs all brought up online before devices
> are resumed? If so, the max_active should already be way higher than the
> WQ_DFL_MIN_ACTIVE. Also, are these multi node NUMA machines? Otherwise, it
> really shouldn't affect anything. One easy way to verify would be just
> bumping up WQ_DFL_MIN_ACTIVE and see what happens.

I've increased WQ_DFL_MIN_ACTIVE from 8 to 32 and all the system 
suspend/resume issues went away. :)

Best regards
-- 
Marek Szyprowski, PhD
Samsung R&D Institute Poland