From: "Martin K. Petersen" <martin.petersen@oracle.com>
To: Sagi Grimberg <sagig@dev.mellanox.co.il>
Cc: Christoph Hellwig <hch@lst.de>,
viro@zeniv.linux.org.uk, axboe@fb.com, milosz@adfin.com,
linux-fsdevel@vger.kernel.org, linux-block@vger.kernel.org,
linux-api@vger.kernel.org
Subject: Re: selective block polling and preadv2/pwritev2 revisited
Date: Wed, 06 Jan 2016 17:49:21 -0500 [thread overview]
Message-ID: <yq1h9iqiary.fsf@sermon.lab.mkp.net> (raw)
In-Reply-To: <568D4859.4010206@dev.mellanox.co.il> (Sagi Grimberg's message of "Wed, 6 Jan 2016 19:01:13 +0200")
>>>>> "Sagi" == Sagi Grimberg <sagig@dev.mellanox.co.il> writes:
>> The idea that was floated aroud a few times was to have a flag where
>> the first half of the vectors would be the data, and the second half
>> the metadata.
Sagi> This means that the user would need to pass iovec entries of 8
Sagi> bytes correct? Seems like a waste for large IOs (sorry for
Sagi> diverging from the subject)
The assumption was that there would be a 1:1 mapping between the number
of data buffers and the metadata ditto. But nothing says that a data
iovec entry is limited in size to a single sector.
The other option to have a single iovec at the end representing the
metadata for all data buffers. I think there are valid use cases for
either approach and we may end up having to support both via a flag.
--
Martin K. Petersen Oracle Linux Engineering
next prev parent reply other threads:[~2016-01-06 22:49 UTC|newest]
Thread overview: 12+ messages / expand[flat|nested] mbox.gz Atom feed top
2015-12-24 14:14 selective block polling and preadv2/pwritev2 revisited Christoph Hellwig
[not found] ` <1450966464-6847-1-git-send-email-hch-jcswGhMUV9g@public.gmane.org>
2015-12-24 14:14 ` [PATCH 1/6] vfs: pass a flags argument to vfs_readv/vfs_writev Christoph Hellwig
2015-12-24 14:14 ` [PATCH 2/6] vfs: vfs: Define new syscalls preadv2,pwritev2 Christoph Hellwig
2015-12-24 14:14 ` [PATCH 3/6] x86: wire up preadv2 and pwritev2 Christoph Hellwig
2016-01-04 14:58 ` selective block polling and preadv2/pwritev2 revisited Sagi Grimberg
[not found] ` <568A889E.4020204-LDSdmyG8hGV8YrgS2mwiifqBs+8SCbDb@public.gmane.org>
2016-01-04 16:39 ` Christoph Hellwig
[not found] ` <20160104163949.GA17409-jcswGhMUV9g@public.gmane.org>
2016-01-06 17:01 ` Sagi Grimberg
2016-01-06 22:49 ` Martin K. Petersen [this message]
[not found] ` <yq1h9iqiary.fsf-+q57XtR/GgMb6DWv4sQWN6xOck334EZe@public.gmane.org>
2016-01-07 14:41 ` Sagi Grimberg
2015-12-24 14:14 ` [PATCH 4/6] vfs: add the RWF_HIPRI flag for preadv2/pwritev2 Christoph Hellwig
2015-12-24 14:14 ` [PATCH 5/6] direct-io: only use block polling if explicitly requested Christoph Hellwig
2015-12-24 14:14 ` [PATCH 6/6] blk-mq: enable polling support by default Christoph Hellwig
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