From: Phillip Susi <psusi@ubuntu.com>
To: dgilbert@interlog.com,
James Bottomley <James.Bottomley@HansenPartnership.com>
Cc: todd.e.brandt@linux.intel.com, linux-ide@vger.kernel.org,
linux-scsi@vger.kernel.org, tj@kernel.org
Subject: Re: [PATCH 1/3] sd: don't bother spinning up disks on resume
Date: Sun, 17 Nov 2013 20:06:14 -0500 [thread overview]
Message-ID: <52896806.4040907@ubuntu.com> (raw)
In-Reply-To: <5289573A.9070307@interlog.com>
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On 11/17/2013 06:54 PM, Douglas Gilbert wrote:
> Even if the SCSI EH code does spin-up the disk, it is inefficient
> and undesirable to send a device into EH for what is a normal,
> predictable situation (i.e. that a SCSI disk will need a START STOP
> UNIT (start) command as part of a resume operation).
The device doesn't need the START STOP UNIT command as part of the
resume operation; it only needs it prior to other commands. What is
inefficient is starting up drives that won't be accessed. I don't see
anything particularly inefficient about issuing the command in the eh
path ( in fact, libata always uses the eh path to handle power
management ). You can of course, use the manage_start_stop flag to
have the disk start on resume if you really want.
> A big server machine could have thousands of SCSI disks (many
> potentially virtual). Sending them all into EH during a resume
> would be a really good test for EH, but horrible for performance.
> If I was designing the SCSI EH I would probably assume not all
> disks would go into EH at roughly the same time. Also if that many
> devices went into EH on the same controller (HBA) it might be
> reasonable to assume that the controller they share needs
> resetting.
They don't all go into EH during resume; they go into EH when they are
finally accessed, which for many of them is probably not for some
time. This also sounds like a bit of speculation and/or hand waving.
Is there really a problem with multiple devices going into EH?
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next prev parent reply other threads:[~2013-11-18 1:06 UTC|newest]
Thread overview: 165+ messages / expand[flat|nested] mbox.gz Atom feed top
2013-10-17 19:33 [PATCH/RESEND v2 0/2] SATA disk resume time optimization Todd E Brandt
2013-11-07 1:53 ` Phillip Susi
2013-11-07 1:57 ` [PATCH 1/3] sd: don't bother spinning up disks on resume Phillip Susi
2013-11-07 18:21 ` Douglas Gilbert
2013-11-07 21:16 ` Phillip Susi
2013-11-16 18:20 ` James Bottomley
2013-11-17 3:50 ` Phillip Susi
2013-11-17 6:43 ` James Bottomley
2013-11-17 16:15 ` Phillip Susi
2013-11-17 23:54 ` Douglas Gilbert
2013-11-18 1:06 ` Phillip Susi [this message]
2013-11-18 15:54 ` Phillip Susi
2013-11-20 14:23 ` Mark Lord
2013-11-20 14:48 ` Phillip Susi
2013-11-28 1:39 ` Phillip Susi
2013-11-18 0:09 ` James Bottomley
2013-11-18 1:11 ` Phillip Susi
2013-11-16 5:23 ` Mark Lord
2013-11-16 14:52 ` Phillip Susi
2013-11-07 1:57 ` [PATCH 2/3] libata: resume in the background Phillip Susi
2013-11-07 1:57 ` [PATCH 3/3] libata: don't start disks on resume Phillip Susi
2013-11-09 1:20 ` [PATCH/RESEND v2 0/2] SATA disk resume time optimization Todd E Brandt
2013-11-09 20:59 ` Phillip Susi
2013-11-09 21:03 ` [PATCH 0/6] Let sleeping disks lie Phillip Susi
2013-12-16 23:30 ` Phillip Susi
2013-12-16 23:30 ` [PATCH 1/6] libata: use sleep instead of standby command Phillip Susi
2013-12-16 23:30 ` [PATCH 2/6] libata: avoid waking disk for several commands Phillip Susi
2013-12-16 23:30 ` [PATCH 3/6] libata: resume in the background Phillip Susi
2014-01-10 22:26 ` Dan Williams
2014-01-11 2:25 ` Phillip Susi
2014-01-11 3:11 ` Dan Williams
2013-12-16 23:30 ` [PATCH 4/6] libata: don't start disks on resume Phillip Susi
2013-12-16 23:30 ` [PATCH 5/6] sd: don't start disks on system resume Phillip Susi
2013-12-17 6:43 ` James Bottomley
2013-12-17 15:01 ` Phillip Susi
2013-12-17 17:48 ` James Bottomley
2013-12-17 18:30 ` Phillip Susi
2013-12-16 23:30 ` [PATCH 6/6] libata: return power status in REQUEST SENSE command Phillip Susi
2013-12-17 18:02 ` Sergei Shtylyov
2013-12-17 18:35 ` Phillip Susi
2014-01-06 2:14 ` REQ_PM vs REQ_TYPE_PM_RESUME Phillip Susi
2014-01-06 7:36 ` Sujit Reddy Thumma
2014-01-06 9:15 ` Aaron Lu
2014-01-06 14:40 ` Phillip Susi
2014-01-06 15:38 ` Alan Stern
2014-01-07 2:44 ` Phillip Susi
2014-01-07 15:20 ` Alan Stern
2014-01-07 15:40 ` Phillip Susi
2014-01-07 15:56 ` Alan Stern
2014-01-09 18:29 ` Douglas Gilbert
2014-01-09 19:20 ` Phillip Susi
2014-01-10 5:23 ` Douglas Gilbert
2014-01-10 14:29 ` Phillip Susi
2014-01-07 7:49 ` Aaron Lu
2014-01-07 14:50 ` Phillip Susi
2014-01-08 1:03 ` Aaron Lu
2014-01-08 1:16 ` Phillip Susi
2014-01-08 1:32 ` Aaron Lu
2014-01-08 1:53 ` Phillip Susi
2014-01-08 2:11 ` Aaron Lu
2014-01-08 2:19 ` Phillip Susi
2014-01-08 2:36 ` Aaron Lu
2014-01-08 5:24 ` Phillip Susi
2014-01-08 7:00 ` Aaron Lu
2014-01-08 19:30 ` Phillip Susi
2014-01-07 15:25 ` Alan Stern
2014-01-07 15:43 ` Phillip Susi
2014-01-07 16:08 ` Alan Stern
2014-01-07 16:37 ` Phillip Susi
2014-01-07 18:05 ` Alan Stern
2014-01-07 18:43 ` Phillip Susi
2014-01-07 19:18 ` Alan Stern
2014-01-07 23:47 ` Phillip Susi
2014-01-08 17:46 ` Alan Stern
2014-01-08 18:31 ` Alan Stern
2014-01-08 20:44 ` Allow runtime suspend during system resume Alan Stern
2014-01-08 21:17 ` Phillip Susi
2014-01-08 21:34 ` Alan Stern
2014-01-09 10:14 ` Ulf Hansson
2014-01-09 15:41 ` Alan Stern
2014-01-08 22:55 ` Rafael J. Wysocki
2014-01-08 23:24 ` Alan Stern
2014-01-09 0:05 ` Rafael J. Wysocki
2014-01-09 15:32 ` Alan Stern
2014-01-09 15:50 ` Phillip Susi
2014-01-09 16:08 ` Alan Stern
2014-01-09 16:30 ` Phillip Susi
2014-01-09 17:04 ` Alan Stern
2014-01-10 1:25 ` Rafael J. Wysocki
2014-01-10 1:55 ` Phillip Susi
2014-01-10 13:35 ` Rafael J. Wysocki
2014-01-10 14:46 ` Phillip Susi
2014-01-10 15:25 ` Alan Stern
2014-01-10 23:02 ` Rafael J. Wysocki
2014-01-11 2:08 ` Phillip Susi
2014-01-11 22:50 ` Alan Stern
2014-01-12 1:50 ` Phillip Susi
2014-01-11 22:34 ` Alan Stern
2014-01-08 20:20 ` REQ_PM vs REQ_TYPE_PM_RESUME Phillip Susi
2014-01-08 21:21 ` Alan Stern
2014-01-08 21:50 ` Phillip Susi
2014-01-09 1:29 ` Aaron Lu
2014-01-09 12:17 ` Rafael J. Wysocki
2014-01-09 13:18 ` Rafael J. Wysocki
2014-01-09 15:40 ` Alan Stern
2014-01-09 15:53 ` Phillip Susi
2014-01-09 16:14 ` Alan Stern
2014-01-09 16:34 ` Phillip Susi
2014-01-09 17:06 ` Alan Stern
2014-01-16 16:59 ` Disk spin-up optimization during system resume Alan Stern
2014-01-16 18:04 ` Todd E Brandt
2014-01-16 18:33 ` Phillip Susi
2014-01-16 20:05 ` Alan Stern
2014-01-16 22:04 ` Todd E Brandt
2014-01-17 14:57 ` Alan Stern
2014-01-17 19:31 ` Dan Williams
2014-01-17 20:15 ` Alan Stern
2014-01-17 20:24 ` Tejun Heo
2014-01-17 20:55 ` Phillip Susi
2014-01-18 14:04 ` Tejun Heo
2014-01-18 1:36 ` Todd E Brandt
2014-01-18 1:41 ` Alan Stern
2014-01-18 2:15 ` Dan Williams
2014-01-18 2:33 ` Alan Stern
2014-01-18 3:24 ` Phillip Susi
2014-01-18 13:59 ` Tejun Heo
2014-01-17 20:49 ` Phillip Susi
2014-01-17 22:17 ` Dan Williams
2014-01-18 3:18 ` Phillip Susi
2014-01-18 4:09 ` Dan Williams
2014-01-18 14:08 ` Alan Stern
2014-01-21 10:12 ` Dan Williams
2014-01-21 14:37 ` Phillip Susi
2014-01-21 16:03 ` Alan Stern
2014-01-21 16:18 ` Phillip Susi
2014-01-21 16:49 ` Alan Stern
2014-01-21 15:44 ` Alan Stern
2014-01-21 16:18 ` Dan Williams
2014-01-21 16:55 ` Dan Williams
2014-01-20 12:38 ` CrashPlan Pro
2014-01-20 14:30 ` Phillip Susi
2014-01-18 1:24 ` Todd E Brandt
2014-01-18 3:20 ` Phillip Susi
2014-01-16 18:39 ` Phillip Susi
2014-01-16 20:08 ` Alan Stern
2014-01-17 10:16 ` Oliver Neukum
2014-01-17 10:21 ` Tejun Heo
2014-01-17 18:18 ` Alan Stern
2014-01-17 18:39 ` James Bottomley
2014-01-17 19:07 ` Tejun Heo
2013-11-09 21:03 ` [PATCH 1/6] libata: use sleep instead of standby command Phillip Susi
2013-11-09 21:03 ` [PATCH 2/6] libata: avoid waking disk to check power Phillip Susi
2013-11-11 13:05 ` Sergei Shtylyov
2013-11-09 21:03 ` [PATCH 3/6] sd: don't bother spinning up disks on resume Phillip Susi
2013-11-11 13:08 ` Sergei Shtylyov
2013-11-11 14:28 ` Phillip Susi
2013-11-09 21:03 ` [PATCH 4/6] libata: resume in the background Phillip Susi
2013-11-11 13:10 ` Sergei Shtylyov
2013-11-09 21:03 ` [PATCH 5/6] libata: don't start disks on resume Phillip Susi
2013-11-09 21:03 ` [PATCH 6/6] libata: fake some more commands when drive is sleeping Phillip Susi
2013-11-11 16:59 ` [PATCH/RESEND v2 0/2] SATA disk resume time optimization Todd E Brandt
2013-11-11 17:08 ` Phillip Susi
2013-12-17 12:15 ` Tejun Heo
2013-12-17 14:24 ` Phillip Susi
2013-11-27 16:18 ` Phillip Susi
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