linux-kernel - Selecting CPUs for queuing work on

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Message-ID: <82233e68-106f-39e9-b20d-7794eb7a8933@amd.com>
Date:   Fri, 12 Aug 2022 16:26:47 -0400
From:   Felix Kuehling <felix.kuehling@....com>
To:     Tejun Heo <tj@...nel.org>, Lai Jiangshan <jiangshanlai@...il.com>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
Cc:     Dave Airlie <airlied@...il.com>, Philip Yang <Philip.Yang@....com>,
        Maling list - DRI developers 
        <dri-devel@...ts.freedesktop.org>,
        "amd-gfx@...ts.freedesktop.org" <amd-gfx@...ts.freedesktop.org>
Subject: Selecting CPUs for queuing work on

Hi workqueue maintainers,

In the KFD (amdgpu) driver we found a need to schedule bottom half 
interrupt handlers on CPU cores different from the one where the 
top-half interrupt handler runs to avoid the interrupt handler stalling 
the bottom half in extreme scenarios. See my latest patch that tries to 
use a different hyperthread on the same CPU core, or falls back to a 
different core in the same NUMA node if that fails: 
https://lore.kernel.org/all/20220811190433.1213179-1-Felix.Kuehling@amd.com/

Dave pointed out that the driver may not be the best place to implement 
such logic and suggested that we should have an abstraction, maybe in 
the workqueue code. Do you feel this is something that could or should 
be provided by the core workqueue code? Or maybe some other place?

Thank you,
   Felix

-- 
F e l i x   K u e h l i n g
PMTS Software Development Engineer | Linux Compute Kernel
1 Commerce Valley Dr. East, Markham, ON L3T 7X6 Canada
(O) +1(289)695-1597
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