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From: "Martin K. Petersen" <martin.petersen@oracle.com>
To: Douglas Gilbert <dgilbert@interlog.com>
Cc: linux-scsi@vger.kernel.org, martin.petersen@oracle.com,
	jejb@linux.vnet.ibm.com, hare@suse.de, Damien.LeMoal@wdc.com
Subject: Re: [PATCH v4 06/14] scsi_debug: implement pre-fetch commands
Date: Mon, 13 Apr 2020 18:57:51 -0400	[thread overview]
Message-ID: <yq1eesrvvrk.fsf@oracle.com> (raw)
In-Reply-To: <20200225062351.21267-7-dgilbert@interlog.com> (Douglas Gilbert's message of "Tue, 25 Feb 2020 01:23:43 -0500")


Doug,

> Many disks implement the SCSI PRE-FETCH commands. One use case might
> be a disk-to-disk compare, say between disks A and B.  Then this
> sequence of commands might be used: PRE-FETCH(from B, IMMED),
> READ(from A), VERIFY (BYTCHK=1 on B with data returned from READ). The
> PRE-FETCH (which returns quickly due to the IMMED) fetches the data
> from the media into B's cache which should speed the trailing VERIFY
> command.  The next chunk of the compare might be done in parallel,
> with A and B reversed.

Minor nit: I agree with the code and the use case. But the commit
description should reflect what the code actually does (not much in the
absence of cache, etc.)

-- 
Martin K. Petersen	Oracle Linux Engineering

  reply	other threads:[~2020-04-13 23:00 UTC|newest]

Thread overview: 31+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-02-25  6:23 [PATCH v4 00/14] scsi_debug: host managed ZBC + doublestore Douglas Gilbert
2020-02-25  6:23 ` [PATCH v4 01/14] scsi_debug: randomize command completion time Douglas Gilbert
2020-04-13 22:24   ` Martin K. Petersen
2020-02-25  6:23 ` [PATCH v4 02/14] scsi_debug: add doublestore option Douglas Gilbert
2020-04-13 22:36   ` Martin K. Petersen
2020-02-25  6:23 ` [PATCH v4 03/14] scsi_debug: implement verify(10), add verify(16) Douglas Gilbert
2020-04-13 22:48   ` Martin K. Petersen
2020-02-25  6:23 ` [PATCH v4 04/14] scsi_debug: weaken rwlock around ramdisk access Douglas Gilbert
2020-02-25  6:23 ` [PATCH v4 05/14] scsi_debug: improve command duration calculation Douglas Gilbert
2020-04-13 22:50   ` Martin K. Petersen
2020-02-25  6:23 ` [PATCH v4 06/14] scsi_debug: implement pre-fetch commands Douglas Gilbert
2020-04-13 22:57   ` Martin K. Petersen [this message]
2020-04-19 18:01     ` Douglas Gilbert
2020-04-19 18:22       ` Julian Wiedmann
2020-04-19 21:53         ` Douglas Gilbert
2020-02-25  6:23 ` [PATCH v4 07/14] scsi_debug: expand zbc support Douglas Gilbert
2020-04-13 23:00   ` Martin K. Petersen
2020-04-13 23:05     ` Damien Le Moal
2020-04-13 23:06       ` Damien Le Moal
2020-04-14  1:55         ` Martin K. Petersen
2020-04-14  5:38           ` Damien Le Moal
2020-02-25  6:23 ` [PATCH v4 08/14] scsi_debug: add zone commands Douglas Gilbert
2020-02-25  6:23 ` [PATCH v4 09/14] scsi_debug: add zbc parameter Douglas Gilbert
2020-04-15  2:10   ` Martin K. Petersen
2020-02-25  6:23 ` [PATCH v4 10/14] scsi_debug: re-arrange parameters alphabetically Douglas Gilbert
2020-02-25  6:23 ` [PATCH v4 11/14] scsi_debug: zone_max_open module parameter Douglas Gilbert
2020-02-25  6:23 ` [PATCH v4 12/14] scsi_debug: zone_nr_conv " Douglas Gilbert
2020-02-25  6:23 ` [PATCH v4 13/14] scsi_debug: zone_size_mb " Douglas Gilbert
2020-02-25  6:23 ` [PATCH v4 14/14] scsi_debug: bump to version 1.89 Douglas Gilbert
2020-04-13 23:19 ` [PATCH v4 00/14] scsi_debug: host managed ZBC + doublestore Martin K. Petersen
2020-04-14  2:49   ` Douglas Gilbert

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