linux-kernel - Re: [PATCH] io_uring: One wqe per wq

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Message-ID: <ac6a2da7-aa88-b119-6a44-01d2f2ec9b6d@kernel.dk>
Date:   Fri, 10 Mar 2023 13:38:20 -0700
From:   Jens Axboe <axboe@...nel.dk>
To:     Breno Leitao <leitao@...ian.org>, asml.silence@...il.com,
        io-uring@...r.kernel.org
Cc:     leit@...com, linux-kernel@...r.kernel.org
Subject: Re: [PATCH] io_uring: One wqe per wq

On 3/10/23 1:11 PM, Breno Leitao wrote:
> Right now io_wq allocates one io_wqe per NUMA node.  As io_wq is now
> bound to a task, the task basically uses only the NUMA local io_wqe, and
> almost never changes NUMA nodes, thus, the other wqes are mostly
> unused.

What if the task gets migrated to a different node? Unless the task
is pinned to a node/cpumask that is local to that node, it will move
around freely.

I'm not a huge fan of the per-node setup, but I think the reasonings
given in this patch are a bit too vague and we need to go a bit
deeper on what a better setup would look like.

-- 
Jens Axboe