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From: FUJITA Tomonori <fujita.tomonori@lab.ntt.co.jp>
To: bharrosh@panasas.com
Cc: fujita.tomonori@lab.ntt.co.jp,
	James.Bottomley@HansenPartnership.com, jens.axboe@oracle.com,
	rdreier@cisco.com, linux-kernel@vger.kernel.org,
	linux-fsdevel@vger.kernel.org, chris.mason@oracle.com,
	david@fromorbit.com, hch@infradead.org,
	akpm@linux-foundation.org, jack@suse.cz,
	yanmin_zhang@linux.intel.com, linux-scsi@vger.kernel.org
Subject: Re: [PATCH 03/13] scsi: unify allocation of scsi command and sense buffer
Date: Wed, 27 May 2009 10:36:40 +0900	[thread overview]
Message-ID: <20090527103637W.fujita.tomonori@lab.ntt.co.jp> (raw)
In-Reply-To: <4A1C1331.8060304@panasas.com>

On Tue, 26 May 2009 19:05:05 +0300
Boaz Harrosh <bharrosh@panasas.com> wrote:

> On 05/26/2009 06:31 PM, FUJITA Tomonori wrote:
> > 
> > Can we just fix some drivers not to do the DMA with the sense buffer in
> > scsi_cmnd? IIRC, there are only five or six drivers that do such.
> 
> This is not so.
> All drivers that go through scsi_eh_prep_cmnd() will eventually DMA through
> the regular read path. Including all the drivers that do nothing and let
> scsi-ml do the REQUEST_SENSE
> 
> Actually I have exact numbers, from the last time I did all that

Hmm, we discussed this before, I think.

scsi-ml uses scsi_eh_prep_cmnd only via scsi_send_eh_cmnd(). There are
some users of scsi_send_eh_cmnd in scsi-ml but only scsi_request_sense
does the DMA in the sense_buffer of scsi_cmnd.

Only scsi_error_handler() uses scsi_request_sense() and
scsi_send_eh_cmnd() works synchronously. So scsi-ml can easily avoid
the the DMA in the sense_buffer of scsi_cmnd if we have one sense
buffer per scsi_host.

  reply	other threads:[~2009-05-27  1:38 UTC|newest]

Thread overview: 61+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2009-05-25  7:30 [PATCH 0/12] Per-bdi writeback flusher threads #5 Jens Axboe
2009-05-25  7:30 ` [PATCH 01/13] libata: get rid of ATA_MAX_QUEUE loop in ata_qc_complete_multiple() Jens Axboe
2009-05-25  7:30 ` [PATCH 01/12] ntfs: remove old debug check for dirty data in ntfs_put_super() Jens Axboe
2009-05-25  7:30 ` [PATCH 02/13] block: add static rq allocation cache Jens Axboe
2009-05-25  7:30 ` [PATCH 02/12] btrfs: properly register fs backing device Jens Axboe
2009-05-25  7:30 ` [PATCH 03/13] scsi: unify allocation of scsi command and sense buffer Jens Axboe
2009-05-25  7:41   ` Christoph Hellwig
2009-05-25  7:46     ` Jens Axboe
2009-05-25  7:50       ` Christoph Hellwig
2009-05-25  7:54         ` Jens Axboe
2009-05-25 10:33         ` Boaz Harrosh
2009-05-25 10:42           ` Christoph Hellwig
2009-05-25 10:49             ` Jens Axboe
2009-05-26  4:36         ` FUJITA Tomonori
2009-05-26  5:08           ` FUJITA Tomonori
2009-05-25  8:15   ` Pekka Enberg
2009-05-25  8:15     ` Pekka Enberg
2009-05-25 11:32     ` Nick Piggin
2009-05-25  9:28   ` Boaz Harrosh
2009-05-26  1:45     ` Roland Dreier
2009-05-26  4:36       ` FUJITA Tomonori
2009-05-26  6:29         ` Jens Axboe
2009-05-26  7:25           ` FUJITA Tomonori
2009-05-26  7:32             ` Jens Axboe
2009-05-26  7:38               ` FUJITA Tomonori
2009-05-26 14:47                 ` James Bottomley
2009-05-26 15:13                   ` Matthew Wilcox
2009-05-26 15:31                   ` FUJITA Tomonori
2009-05-26 16:05                     ` Boaz Harrosh
2009-05-27  1:36                       ` FUJITA Tomonori [this message]
2009-05-27  7:54                         ` Boaz Harrosh
2009-05-27  8:26                           ` FUJITA Tomonori
2009-05-27  9:11                             ` Boaz Harrosh
2009-05-26 16:12                   ` Boaz Harrosh
2009-05-26 16:28                     ` Boaz Harrosh
2009-05-26  7:56               ` FUJITA Tomonori
2009-05-26  5:23     ` FUJITA Tomonori
2009-05-25  7:30 ` [PATCH 03/12] writeback: move dirty inodes from super_block to backing_dev_info Jens Axboe
2009-05-25  7:30 ` [PATCH 04/13] scsi: get rid of lock in __scsi_put_command() Jens Axboe
2009-05-25  7:30 ` [PATCH 04/12] writeback: switch to per-bdi threads for flushing data Jens Axboe
2009-05-25  7:30 ` [PATCH 05/13] aio: mostly crap Jens Axboe
2009-05-25  9:09   ` Jan Kara
2009-05-25  7:30 ` [PATCH 05/12] writeback: get rid of pdflush completely Jens Axboe
2009-05-25  7:30 ` [PATCH 06/13] block: move elevator ops into the queue Jens Axboe
2009-05-25  7:30 ` [PATCH 06/12] writeback: separate the flushing state/task from the bdi Jens Axboe
2009-05-25  7:30 ` [PATCH 07/13] block: avoid indirect calls to enter cfq io scheduler Jens Axboe
2009-05-26  9:02   ` Nikanth K
2009-05-26  9:02     ` Nikanth K
2009-05-25  7:30 ` [PATCH 07/12] writeback: support > 1 flusher thread per bdi Jens Axboe
2009-05-25  7:30 ` [PATCH 08/13] block: change the tag sync vs async restriction logic Jens Axboe
2009-05-25  7:30 ` [PATCH 08/12] writeback: include default_backing_dev_info in writeback Jens Axboe
2009-05-25  7:31 ` [PATCH 09/13] libata: switch to using block layer tagging support Jens Axboe
2009-05-25  7:31 ` [PATCH 09/12] writeback: allow sleepy exit of default writeback task Jens Axboe
2009-05-25  7:31 ` [PATCH 10/13] block: add function for waiting for a specific free tag Jens Axboe
2009-05-25  7:31 ` [PATCH 10/12] writeback: add some debug inode list counters to bdi stats Jens Axboe
2009-05-25  7:31 ` [PATCH 11/13] block: disallow merging of read-ahead bits into normal request Jens Axboe
2009-05-25  7:31 ` [PATCH 11/12] writeback: add name to backing_dev_info Jens Axboe
2009-05-25  7:31 ` [PATCH 12/13] block: first cut at implementing a NAPI approach for block devices Jens Axboe
2009-05-25  7:31 ` [PATCH 12/12] writeback: check for registered bdi in flusher add and inode dirty Jens Axboe
2009-05-25  7:31 ` [PATCH 13/13] block: unlocked completion test patch Jens Axboe
2009-05-25  7:33 ` [PATCH 0/12] Per-bdi writeback flusher threads #5 Jens Axboe

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