linux-kernel - Re: [RFC workqueue/driver-core PATCH 1/5] workqueue: Provide queue_work_near to queue work near a given NUMA node

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Message-ID: <9b002bbb-3e6d-9e99-d8f9-36df4306093e@linux.intel.com>
Date:   Wed, 26 Sep 2018 15:05:17 -0700
From:   Alexander Duyck <alexander.h.duyck@...ux.intel.com>
To:     Tejun Heo <tj@...nel.org>
Cc:     linux-nvdimm@...ts.01.org, gregkh@...uxfoundation.org,
        linux-pm@...r.kernel.org, linux-kernel@...r.kernel.org,
        akpm@...ux-foundation.org, len.brown@...el.com,
        dave.jiang@...el.com, rafael@...nel.org, vishal.l.verma@...el.com,
        jiangshanlai@...il.com, pavel@....cz, zwisler@...nel.org,
        dan.j.williams@...el.com
Subject: Re: [RFC workqueue/driver-core PATCH 1/5] workqueue: Provide
 queue_work_near to queue work near a given NUMA node



On 9/26/2018 2:53 PM, Tejun Heo wrote:
> Hello,
> 
> On Wed, Sep 26, 2018 at 02:51:38PM -0700, Alexander Duyck wrote:
>> This patch provides a new function queue_work_near which is meant to
>> schedule work on the nearest unbound CPU to the requested NUMA node. The
>> main motivation for this is to help assist asynchronous init to better
>> improve boot times for devices that are local to a specific node.
>>
>> Signed-off-by: Alexander Duyck <alexander.h.duyck@...ux.intel.com>
> 
> Why not just use unbound workqueues, which are NUMA-affine by default?
> Are there big enough advantages?
> 
> Thanks.

I am using unbound workqueues. However there isn't an interface that 
exposes the NUMA bits of them directly. All I am doing with this patch 
is adding "queue_work_near" which takes a NUMA node as an argument and 
then copies the logic of "queue_work_on" with the exception that I am 
doing a check to verify that there is an intersection between 
wq_unbound_cpumask and the cpumask of the node, and then passing a CPU 
from that intersection into "__queue_work".

Thanks.

- Alex