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From: Ming Lei <ming.lei@canonical.com>
To: Christoph Hellwig <hch@infradead.org>
Cc: linux-kernel@vger.kernel.org,
	Dave Kleikamp <dave.kleikamp@oracle.com>,
	Jens Axboe <axboe@kernel.dk>, Zach Brown <zab@zabbo.net>,
	Maxim Patlasov <mpatlasov@parallels.com>,
	Andrew Morton <akpm@linux-foundation.org>,
	Alexander Viro <viro@zeniv.linux.org.uk>,
	Benjamin LaHaise <bcrl@kvack.org>, Jeff Moyer <jmoyer@redhat.com>
Subject: Re: [PATCH v2 3/4] block: loop: introduce 'use_aio' sysfs file
Date: Tue, 27 Jan 2015 13:26:54 +0800	[thread overview]
Message-ID: <CACVXFVOgMvccTUZB91OZFgjc_zQk0VnhxtBTO0OhwRYBye8Xnw@mail.gmail.com> (raw)
In-Reply-To: <20150125133514.GC19445@infradead.org>

On 1/25/15, Christoph Hellwig <hch@infradead.org> wrote:
> On Tue, Jan 13, 2015 at 11:44:47PM +0800, Ming Lei wrote:
>> So that users can control if kernel aio is used to submit I/O.
>
> Why do you want a sysfs flag for this instead of a flags in ->lo_flags
> at setup time?  That's how all other loop-related ABI flags work.

The flag only effects performance or CPU/memory resource utilization,
and I plan to change it as dio flag.

On Tue, Jan 27, 2015 at 1:57 AM, Jeff Moyer <jmoyer@redhat.com> wrote:
> Ming Lei <ming.lei@canonical.com> writes:
>
>> So that users can control if kernel aio is used to submit I/O.
>
> How would a user know to choose aio or, um, /not/ aio?  At the very
> least, documentation is required for this.  I'd rather see the option
> disappear completely, though.

As the comment says in patch 4/4, using direct I/O can save memory/CPU
a lot, and won't hurt throughput if I/O is from filesystem. Otherwise,
user may choose to not use direct I/O for sake of throughput.


Thanks,
Ming Lei

  reply	other threads:[~2015-01-27  5:26 UTC|newest]

Thread overview: 22+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2015-01-13 15:44 [PATCH v2 0/4] block & aio: improve loop with kernel aio Ming Lei
2015-01-13 15:44 ` [PATCH v2 1/4] aio: add aio_kernel_() interface Ming Lei
2015-01-25 13:31   ` Christoph Hellwig
2015-01-26 16:18     ` Ming Lei
2015-01-26 17:00       ` Christoph Hellwig
2015-01-27 13:57         ` Ming Lei
2015-01-27 17:59       ` Christoph Hellwig
2015-01-13 15:44 ` [PATCH v2 2/4] fd/direct-io: introduce should_dirty for kernel aio Ming Lei
2015-01-25 13:34   ` Christoph Hellwig
2015-01-27 16:05     ` Ming Lei
2015-01-13 15:44 ` [PATCH v2 3/4] block: loop: introduce 'use_aio' sysfs file Ming Lei
2015-01-25 13:35   ` Christoph Hellwig
2015-01-27  5:26     ` Ming Lei [this message]
2015-01-26 17:57   ` Jeff Moyer
2015-01-13 15:44 ` [PATCH v2 4/4] block: loop: support to submit I/O via kernel aio based Ming Lei
2015-01-25 13:40   ` Christoph Hellwig
2015-03-18 18:28   ` Maxim Patlasov
2015-03-19  2:57     ` Ming Lei
2015-03-19 16:37       ` Maxim Patlasov
2015-03-20  5:27         ` Ming Lei
2015-01-13 16:23 ` [PATCH v2 0/4] block & aio: improve loop with kernel aio Christoph Hellwig
2015-01-14 10:17   ` Ming Lei

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