From: Sagi Grimberg <sagi@grimberg.me>
To: Tejun Heo <tj@kernel.org>
Cc: Hannes Reinecke <hare@suse.de>, Hannes Reinecke <hare@kernel.org>,
Christoph Hellwig <hch@lst.de>, Keith Busch <kbusch@kernel.org>,
linux-nvme@lists.infradead.org
Subject: Re: [PATCH 1/4] nvme-tcp: per-controller I/O workqueues
Date: Wed, 3 Jul 2024 22:41:38 +0300 [thread overview]
Message-ID: <e78e0939-e58b-42e8-b13d-602e1f880cfd@grimberg.me> (raw)
In-Reply-To: <ZoWjxtyjHTC2r285@slm.duckdns.org>
On 03/07/2024 22:17, Tejun Heo wrote:
> Hello,
>
> On Wed, Jul 03, 2024 at 10:14:14PM +0300, Sagi Grimberg wrote:
> ...
>> None of these reasons are the claimed reason to use separate workqueues in
>> this patch. The claim is that it is more efficient, i.e. has less overhead.
>>
>> The commit msg is the following:
>> "Implement per-controller I/O workqueues to reduce workqueue contention
>> during I/O."
> Hmm... it's not impossible for the concurrency accounting in pool_workqueues
> to show up if the issue rate is *really* high but I'd be surprised if that
> actually matters given that the backend pool is shared. Maybe I'm missing
> something but I don't see a reason why multiple workqueues would be more
> efficient than a shared one.
That was my assumption as well, that there is no real point in using
multiple workqueues.
And hence my surprise.
Hannes, can you please provide a quantitive improvement that you saw simply
by separating to different workqueues?
next prev parent reply other threads:[~2024-07-03 19:41 UTC|newest]
Thread overview: 37+ messages / expand[flat|nested] mbox.gz Atom feed top
2024-07-03 13:50 [PATCH 0/4] nvme-tcp: improve scalability Hannes Reinecke
2024-07-03 13:50 ` [PATCH 1/4] nvme-tcp: per-controller I/O workqueues Hannes Reinecke
2024-07-03 14:11 ` Sagi Grimberg
2024-07-03 14:46 ` Hannes Reinecke
2024-07-03 15:16 ` Sagi Grimberg
2024-07-03 17:07 ` Tejun Heo
2024-07-03 19:14 ` Sagi Grimberg
2024-07-03 19:17 ` Tejun Heo
2024-07-03 19:41 ` Sagi Grimberg [this message]
2024-07-04 7:36 ` Hannes Reinecke
2024-07-05 7:10 ` Christoph Hellwig
2024-07-05 8:11 ` Hannes Reinecke
2024-07-05 8:16 ` Jens Axboe
2024-07-04 5:36 ` Christoph Hellwig
2024-07-03 13:50 ` [PATCH 2/4] nvme-tcp: align I/O cpu with blk-mq mapping Hannes Reinecke
2024-07-03 14:19 ` Sagi Grimberg
2024-07-03 14:53 ` Hannes Reinecke
2024-07-03 15:03 ` Sagi Grimberg
2024-07-03 15:40 ` Hannes Reinecke
2024-07-03 19:38 ` Sagi Grimberg
2024-07-03 19:47 ` Sagi Grimberg
2024-07-04 6:43 ` Hannes Reinecke
2024-07-04 9:07 ` Sagi Grimberg
2024-07-04 14:03 ` Hannes Reinecke
2024-07-04 5:37 ` Christoph Hellwig
2024-07-04 9:13 ` Sagi Grimberg
2024-07-03 13:50 ` [PATCH 3/4] workqueue: introduce helper workqueue_unbound_affinity_scope() Hannes Reinecke
2024-07-03 17:31 ` Tejun Heo
2024-07-04 6:04 ` Hannes Reinecke
2024-07-03 13:50 ` [PATCH 4/4] nvme-tcp: switch to 'cpu' affinity scope for unbound workqueues Hannes Reinecke
2024-07-03 14:22 ` Sagi Grimberg
2024-07-03 15:01 ` Hannes Reinecke
2024-07-03 15:09 ` Sagi Grimberg
2024-07-03 15:50 ` Hannes Reinecke
2024-07-04 9:11 ` Sagi Grimberg
2024-07-04 15:54 ` Hannes Reinecke
2024-07-05 11:48 ` Sagi Grimberg
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