linux-kernel - Re: [PATCH] /dev/mem: nowait zero/null ops

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Message-ID: <YTiPoKc9GiG52DNd@kroah.com>
Date:   Wed, 8 Sep 2021 12:25:36 +0200
From:   Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:     Pavel Begunkov <asml.silence@...il.com>
Cc:     Arnd Bergmann <arnd@...db.de>, linux-kernel@...r.kernel.org,
        Jens Axboe <axboe@...nel.dk>, io-uring@...r.kernel.org
Subject: Re: [PATCH] /dev/mem: nowait zero/null ops

On Wed, Sep 08, 2021 at 11:06:51AM +0100, Pavel Begunkov wrote:
> Make read_iter_zero() to honor IOCB_NOWAIT, so /dev/zero can be
> advertised as FMODE_NOWAIT. This helps subsystems like io_uring to use
> it more effectively. Set FMODE_NOWAIT for /dev/null as well, it never
> waits and therefore trivially meets the criteria.

I do not understand, why would io_uring need to use /dev/zero and how is
this going to help anything?

What workload does this help with?

thanks,

greg k-h