From: Sagi Grimberg <sagig-LDSdmyG8hGV8YrgS2mwiifqBs+8SCbDb@public.gmane.org>
To: Christoph Hellwig <hch-jcswGhMUV9g@public.gmane.org>
Cc: viro-RmSDqhL/yNMiFSDQTTA3OLVCufUGDwFn@public.gmane.org,
axboe-b10kYP2dOMg@public.gmane.org,
milosz-B5zB6C1i6pkAvxtiuMwx3w@public.gmane.org,
linux-fsdevel-u79uwXL29TY76Z2rM5mHXA@public.gmane.org,
linux-block-u79uwXL29TY76Z2rM5mHXA@public.gmane.org,
linux-api-u79uwXL29TY76Z2rM5mHXA@public.gmane.org
Subject: Re: selective block polling and preadv2/pwritev2 revisited
Date: Wed, 6 Jan 2016 19:01:13 +0200 [thread overview]
Message-ID: <568D4859.4010206@dev.mellanox.co.il> (raw)
In-Reply-To: <20160104163949.GA17409-jcswGhMUV9g@public.gmane.org>
>> Hi Christoph,
>>
>>> Note that there are plenty of other use cases for preadv2/pwritev2 as well,
>>> but I'd like to concentrate on this one for now. Example are: non-blocking
>>> reads (the original purpose), per-I/O O_SYNC, user space support for T10
>>> DIF/DIX applications tags and probably some more.
>>
>> So I'm trying to understand how can integrity metadata be used here.
>> Will the user-app append the meta-data to the data iovec (given there
>> is no metadata iovec)? If so, how will we separate data from metadata?
>
> 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.
This means that the user would need to pass iovec entries of 8 bytes
correct? Seems like a waste for large IOs (sorry for diverging from the
subject)
WARNING: multiple messages have this Message-ID (diff)
From: Sagi Grimberg <sagig@dev.mellanox.co.il>
To: Christoph Hellwig <hch@lst.de>
Cc: 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, 6 Jan 2016 19:01:13 +0200 [thread overview]
Message-ID: <568D4859.4010206@dev.mellanox.co.il> (raw)
In-Reply-To: <20160104163949.GA17409@lst.de>
>> Hi Christoph,
>>
>>> Note that there are plenty of other use cases for preadv2/pwritev2 as well,
>>> but I'd like to concentrate on this one for now. Example are: non-blocking
>>> reads (the original purpose), per-I/O O_SYNC, user space support for T10
>>> DIF/DIX applications tags and probably some more.
>>
>> So I'm trying to understand how can integrity metadata be used here.
>> Will the user-app append the meta-data to the data iovec (given there
>> is no metadata iovec)? If so, how will we separate data from metadata?
>
> 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.
This means that the user would need to pass iovec entries of 8 bytes
correct? Seems like a waste for large IOs (sorry for diverging from the
subject)
next prev parent reply other threads:[~2016-01-06 17:01 UTC|newest]
Thread overview: 20+ messages / expand[flat|nested] mbox.gz Atom feed top
2015-12-24 14:14 selective block polling and preadv2/pwritev2 revisited Christoph Hellwig
2015-12-24 14:14 ` 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 ` Christoph Hellwig
2015-12-24 14:14 ` [PATCH 2/6] vfs: vfs: Define new syscalls preadv2,pwritev2 Christoph Hellwig
2015-12-24 14:14 ` Christoph Hellwig
2015-12-24 14:14 ` [PATCH 3/6] x86: wire up preadv2 and pwritev2 Christoph Hellwig
2015-12-24 14:14 ` Christoph Hellwig
2016-01-04 14:58 ` selective block polling and preadv2/pwritev2 revisited Sagi Grimberg
2016-01-04 14:58 ` Sagi Grimberg
[not found] ` <568A889E.4020204-LDSdmyG8hGV8YrgS2mwiifqBs+8SCbDb@public.gmane.org>
2016-01-04 16:39 ` Christoph Hellwig
2016-01-04 16:39 ` Christoph Hellwig
[not found] ` <20160104163949.GA17409-jcswGhMUV9g@public.gmane.org>
2016-01-06 17:01 ` Sagi Grimberg [this message]
2016-01-06 17:01 ` Sagi Grimberg
2016-01-06 22:49 ` Martin K. Petersen
[not found] ` <yq1h9iqiary.fsf-+q57XtR/GgMb6DWv4sQWN6xOck334EZe@public.gmane.org>
2016-01-07 14:41 ` Sagi Grimberg
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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