From: Dmitry Monakhov <dmonakhov@openvz.org>
To: Mike Krinkin <krinkin.m.u@gmail.com>, linux-kernel@vger.kernel.org
Cc: axboe@kernel.dk, hch@lst.de, kmo@daterainc.com
Subject: Re: submit bio directly from userspace
Date: Fri, 09 Oct 2015 14:41:53 +0300 [thread overview]
Message-ID: <87si5kz2ta.fsf@openvz.org> (raw)
In-Reply-To: <20151007144253.GA26518@kmu-tp-x230>
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Mike Krinkin <krinkin.m.u@gmail.com> writes:
> Hi,
>
> i'm developing block layer workload simulator/player and need to
> generate bios as close as possible to the ones in original workload.
> To play workload i employ aio + O_DIRECT, but all IOs end up as bios
> with SYNC flag set. So i wonder is there any way to control bios
> flags from userspace or, maybe, any other options to generate
> workload from userspace except aio + O_DIRECT with more precise
> control over bio flags?
100% agree, I've investigated existing io-load replay tools and
seems that they all use O_DIRECT(like btreplay) or
buffered-aio/{sync_file_range,fadvise} ( like fio).
So it looks like they all very inaccurate.
Jens, what do to do to replay real load in order to test fs/ioscheduler
harness? Are you interested in having such fine-tuning interface
(probably guarded by CAP_SYS_ADMIN)?
There are several places where we can pass such flag
1) iocb->aio_flag, add IOCB_FLAG_DIRECT_ASYNC
2) add new flag O_DIRECT_ASYNC to file->f_flags
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next prev parent reply other threads:[~2015-10-09 11:42 UTC|newest]
Thread overview: 3+ messages / expand[flat|nested] mbox.gz Atom feed top
2015-10-07 14:42 submit bio directly from userspace Mike Krinkin
2015-10-09 11:41 ` Dmitry Monakhov [this message]
2015-10-09 14:32 ` Jens Axboe
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