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From: "Nikanth K" <nikanth@gmail.com>
To: "device-mapper development" <dm-devel@redhat.com>
Cc: jens.axboe@oracle.com, agk@redhat.com,
	James.Bottomley@hansenpartnership.com, j-nomura@ce.jp.nec.com,
	k-ueda@ct.jp.nec.com, linux-kernel@vger.kernel.org,
	linux-scsi@vger.kernel.org,
	"Nikanth Karthikesan" <knikanth@suse.de>
Subject: Re: [dm-devel] [PATCH 11/13] dm: enable request-based dm
Date: Fri, 24 Oct 2008 13:22:46 +0530	[thread overview]
Message-ID: <807b3a220810240052n6a8b41b0x1ea9c88124b3f5f8@mail.gmail.com> (raw)
In-Reply-To: <20080912.104634.08318008.k-ueda@ct.jp.nec.com>

On Fri, Sep 12, 2008 at 8:16 PM, Kiyoshi Ueda <k-ueda@ct.jp.nec.com> wrote:
> This patch enables request-based dm.
>
> o Request-based dm and bio-based dm coexist, since there are
>  some target drivers which are more fitting to bio-based dm.
>  Also, there are other bio-based devices in the kernel
>  (e.g. md, loop).
>  Since bio-based device can't receive struct request,
>  there are some limitations on device stacking between
>  bio-based and request-based.
>
>                     type of underlying device
>                   bio-based      requeset-based
>   ----------------------------------------------
>    bio-based         OK                OK
>    request-based     NG                OK
>

So will some configurations would become impossible, if a target is
made request-based and bio-based one is removed. Hope both
types of targets would co-exist and would be selectable for sometime.

>  The device type is recognized by the queue flag in the kernel,
>  so dm follows that.
>
> o The type of a dm device is decided at the first table loading time.
>  Until then, mempool creations are deferred, since mempools for
>  request-based dm are different from those for bio-based dm.
>  Once the type of a dm device is decided, the type can't be changed.
>
> o Currently, request-based dm supports only tables that have a single
>  target.

Barrier support should be straight forward?

Thanks
Nikanth Karthikesan

  reply	other threads:[~2008-10-24  7:52 UTC|newest]

Thread overview: 26+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2008-09-12 14:38 [PATCH 00/13] request-based dm-multipath Kiyoshi Ueda
2008-09-12 14:40 ` [PATCH 01/13] block: add request update interface Kiyoshi Ueda
2008-09-12 14:41 ` [PATCH 02/13] block: add request submission interface Kiyoshi Ueda
2008-09-14 13:10   ` Boaz Harrosh
2008-09-16 16:06     ` Kiyoshi Ueda
2008-09-16 17:02       ` Jens Axboe
2008-09-16 18:12         ` Kiyoshi Ueda
2008-09-12 14:42 ` [PATCH 03/13] mm: lld busy status exporting interface Kiyoshi Ueda
2008-09-12 14:43 ` [PATCH 04/13] scsi: exports busy status Kiyoshi Ueda
2008-09-12 14:43 ` [PATCH 05/13] block: add a queue flag for request stacking support Kiyoshi Ueda
2008-09-12 14:44 ` [PATCH 06/13] dm: remove unused DM_WQ_FLUSH_ALL Kiyoshi Ueda
2008-09-12 14:44 ` [PATCH 07/13] dm: tidy local_init Kiyoshi Ueda
2008-09-12 14:45 ` [PATCH 08/13] dm: add kmem_cache for request-based dm Kiyoshi Ueda
2008-09-12 14:45 ` [PATCH 09/13] dm: add target interfaces " Kiyoshi Ueda
2008-09-12 14:46 ` [PATCH 10/13] dm: add core functions " Kiyoshi Ueda
2008-10-24  7:44   ` [dm-devel] " Nikanth K
2008-10-28 16:00     ` Kiyoshi Ueda
     [not found]     ` <490FB852.3FEE.00C5.1@novell.com>
     [not found]       ` <49102C03020000C50002E257@victor.provo.novell.com>
2008-11-04 15:01         ` Kiyoshi Ueda
2008-09-12 14:46 ` [PATCH 11/13] dm: enable " Kiyoshi Ueda
2008-10-24  7:52   ` Nikanth K [this message]
2008-10-28 16:02     ` [dm-devel] " Kiyoshi Ueda
2008-09-12 14:46 ` [PATCH 12/13] dm: reject I/O violating new queue limits Kiyoshi Ueda
2008-09-12 14:47 ` [PATCH 13/13] dm-mpath: convert to request-based Kiyoshi Ueda
2008-10-24  7:55   ` [dm-devel] " Nikanth K
2008-10-28 16:03     ` Kiyoshi Ueda
2008-09-14 13:17 ` [PATCH 00/13] request-based dm-multipath Jens Axboe

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