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From: Jan Kara <jack@suse.cz>
To: Avi Kivity <avi@scylladb.com>
Cc: Goldwyn Rodrigues <rgoldwyn@suse.de>,
	jack@suse.com, hch@infradead.org, linux-fsdevel@vger.kernel.org,
	linux-block@vger.kernel.org, linux-btrfs@vger.kernel.org,
	linux-ext4@vger.kernel.org, linux-xfs@vger.kernel.org
Subject: Re: [PATCH 0/8 v2] Non-blocking AIO
Date: Mon, 6 Mar 2017 09:25:46 +0100	[thread overview]
Message-ID: <20170306082546.GA14932@quack2.suse.cz> (raw)
In-Reply-To: <347d19cb-dbb8-1d4f-dfb5-d1dd820dd65d@scylladb.com>

On Sun 05-03-17 16:56:21, Avi Kivity wrote:
> >The goal of the patch series is to return -EAGAIN/-EWOULDBLOCK if
> >any of these conditions are met. This way userspace can push most
> >of the write()s to the kernel to the best of its ability to complete
> >and if it returns -EAGAIN, can defer it to another thread.
> >
> 
> Is it not possible to push the iocb to a workqueue?  This will allow
> existing userspace to work with the new functionality, unchanged. Any
> userspace implementation would have to do the same thing, so it's not like
> we're saving anything by pushing it there.

That is not easy because until IO is fully submitted, you need some parts
of the context of the process which submits the IO (e.g. memory mappings,
but possibly also other credentials). So you would need to somehow transfer
this information to the workqueue.

								Honza
-- 
Jan Kara <jack@suse.com>
SUSE Labs, CR

  reply	other threads:[~2017-03-06  8:52 UTC|newest]

Thread overview: 39+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2017-02-28 23:36 [PATCH 0/8 v2] Non-blocking AIO Goldwyn Rodrigues
2017-02-28 23:36 ` [PATCH 1/8] nowait aio: Introduce IOCB_FLAG_NOWAIT Goldwyn Rodrigues
2017-03-01 15:36   ` Christoph Hellwig
2017-03-01 15:56     ` Christoph Hellwig
2017-03-01 16:57       ` Goldwyn Rodrigues
2017-03-01 22:44         ` Christoph Hellwig
2017-02-28 23:36 ` [PATCH 2/8] nowait aio: Return if cannot get hold of i_rwsem Goldwyn Rodrigues
2017-03-01 15:37   ` Christoph Hellwig
2017-02-28 23:36 ` [PATCH 3/8] nowait aio: return if direct write will trigger writeback Goldwyn Rodrigues
2017-03-01  3:46   ` Matthew Wilcox
2017-03-01 15:38     ` Christoph Hellwig
2017-03-02 10:38       ` Jan Kara
2017-03-02 14:12         ` Matthew Wilcox
2017-03-02 15:22           ` Jan Kara
2017-02-28 23:36 ` [PATCH 4/8] nowait aio: Introduce IOMAP_NOWAIT Goldwyn Rodrigues
2017-02-28 23:36 ` [PATCH 5/8] nowait aio: return on congested block device Goldwyn Rodrigues
2017-03-08  7:03   ` Sagi Grimberg
2017-03-08 15:00     ` Goldwyn Rodrigues
2017-03-08 15:28       ` Jan Kara
2017-03-08 15:51         ` Christoph Hellwig
2017-03-08 16:17       ` Jens Axboe
2017-03-09  2:18         ` Goldwyn Rodrigues
2017-02-28 23:36 ` [PATCH 6/8] nowait aio: ext4 Goldwyn Rodrigues
2017-02-28 23:36 ` [PATCH 7/8] nowait aio: xfs Goldwyn Rodrigues
2017-03-01 15:40   ` Christoph Hellwig
2017-02-28 23:36 ` [PATCH 8/8] nowait aio: btrfs Goldwyn Rodrigues
2017-03-05 14:56 ` [PATCH 0/8 v2] Non-blocking AIO Avi Kivity
2017-03-06  8:25   ` Jan Kara [this message]
2017-03-06  8:40     ` Avi Kivity
2017-03-06 15:19     ` Jens Axboe
2017-03-06 15:29       ` Avi Kivity
2017-03-06 15:38         ` Jens Axboe
2017-03-06 15:59           ` Avi Kivity
2017-03-06 16:08             ` Jens Axboe
2017-03-06 16:59               ` Avi Kivity
2017-03-06 17:06                 ` Jens Axboe
2017-03-06 18:17                   ` Avi Kivity
2017-03-06 18:27                     ` Jens Axboe
2017-03-06 18:50                       ` Avi Kivity

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