From: Jens Axboe <axboe@kernel.dk>
To: Christoph Hellwig <hch@infradead.org>
Cc: "linux-block@vger.kernel.org" <linux-block@vger.kernel.org>
Subject: Re: [PATCH] brd: mark as nowait compatible
Date: Thu, 16 Feb 2023 06:11:41 -0700 [thread overview]
Message-ID: <9a9adcce-81db-580f-843f-ebff7177464c@kernel.dk> (raw)
In-Reply-To: <Y+3IUcJLNK8WAkov@infradead.org>
On 2/15/23 11:08 PM, Christoph Hellwig wrote:
> On Wed, Feb 15, 2023 at 04:43:47PM -0700, Jens Axboe wrote:
>> By default, non-mq drivers do not support nowait. This causes io_uring
>> to use a slower path as the driver cannot be trust not to block. brd
>> can safely set the nowait flag, as worst case all it does is a NOIO
>> allocation.
>
> But a NOIO allocation can block. I think we need to do a
> GFP_NOWAIT allocation in brd_insert_page if the NOWAIT flag is set.
I did consider that, but we do allocations almost everywhere and
as long as we're not waiting on IO, it's mostly considered acceptable.
But I can make that change, no reason not to.
--
Jens Axboe
next prev parent reply other threads:[~2023-02-16 13:11 UTC|newest]
Thread overview: 5+ messages / expand[flat|nested] mbox.gz Atom feed top
2023-02-15 23:43 [PATCH] brd: mark as nowait compatible Jens Axboe
2023-02-16 6:08 ` Christoph Hellwig
2023-02-16 13:11 ` Jens Axboe [this message]
2023-02-16 14:40 ` Christoph Hellwig
2023-02-16 14:48 ` Jens Axboe
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