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From: Tejun Heo <tj@kernel.org>
To: Bart Van Assche <bvanassche@acm.org>
Cc: linux-kernel@vger.kernel.org,
	FUJITA Tomonori <fujita.tomonori@lab.ntt.co.jp>,
	"James E.J. Bottomley" <James.Bottomley@hansenpartnership.com>,
	linux-scsi@vger.kernel.org,
	Brian King <brking@linux.vnet.ibm.com>,
	Robert Jennings <rcj@linux.vnet.ibm.com>
Subject: Re: [PATCH 17/32] scsi/ibmvstgt: use system_wq instead of vtgtd workqueue
Date: Tue, 1 Feb 2011 11:40:43 +0100	[thread overview]
Message-ID: <20110201104043.GH14211@htj.dyndns.org> (raw)
In-Reply-To: <20110124162414.GD27510@htj.dyndns.org>

On Mon, Jan 24, 2011 at 05:24:14PM +0100, Tejun Heo wrote:
> Hello,
> 
> On Mon, Jan 24, 2011 at 05:09:18PM +0100, Bart Van Assche wrote:
> > Insertion of  flush_work_sync() fixes a race - that's a good catch.
> > flush_work_sync() should be invoked a little earlier though because
> > the scheduled work may access the queue destroyed by the
> > crq_queue_destroy(target) call. And the CRQ interrupt should be
> > disabled from before flush_work_sync() is invoked until after the CRQ
> > has been destroyed.
> 
> Heh, I'm a bit out of my depth here.  If you know what's necessary,
> please go ahead and make the change.
> 
> > Regarding the queue removal: I might have missed something, but why
> > would you like to remove the vtgtd work queue ? Since the ibmvstgt
> > driver is a storage target driver, processing latency matters. I'm
> > afraid that switching from a dedicated queue to the global work queue
> > will increase processing latency.
> 
> Having a dedicated workqueue no longer makes any difference regarding
> processing latency.  Each workqueue is mere frontend to the shared
> worker pool anyway.  Dedicated workqueues are now meaningful only as
> forward progress guarantee, attribute and/or flush domain - IOW, when
> the workqueue needs to be used during memory reclaim, the work items
> need to have specific attributes or certain group of work items need
> to be flushed together.  Apart from that, there's virtually no
> difference between using the system_wq and a dedicated one.  As using
> the system one is usually simpler, it's natural to do that.

Ping.  Are you interested in doing the conversion?

Thanks.

-- 
tejun

  reply	other threads:[~2011-02-01 10:40 UTC|newest]

Thread overview: 119+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2011-01-03 13:49 [PATCHSET] workqueue: update workqueue users - replace create_workqueue() Tejun Heo
2011-01-03 13:49 ` [PATCH 01/32] arm/omap: use system_wq in mailbox Tejun Heo
2011-01-03 21:35   ` Kanigeri, Hari
2011-01-04  5:24     ` Tejun Heo
2011-01-25 13:47       ` Tejun Heo
2011-01-25 15:34         ` Hari Kanigeri
2011-01-25 15:34           ` Hari Kanigeri
2011-01-25 15:37           ` Tejun Heo
2011-01-03 13:49 ` [PATCH 02/32] powerpc/cell: use system_wq in cpufreq_spudemand Tejun Heo
2011-01-03 13:49   ` Tejun Heo
2011-01-03 13:49 ` [PATCH 03/32] block: make kblockd_workqueue smarter Tejun Heo
2011-01-03 14:00   ` Jens Axboe
2011-01-03 13:49 ` [PATCH 04/32] bio-integrity: mark kintegrityd_wq highpri and CPU intensive Tejun Heo
2011-01-03 13:49 ` [PATCH 05/32] crypto: mark crypto workqueues CPU_INTENSIVE Tejun Heo
2011-01-03 13:49   ` Tejun Heo
2011-01-04  4:38   ` Herbert Xu
2011-01-04  4:38     ` Herbert Xu
2011-01-03 13:49 ` [PATCH 06/32] acpi: kacpi*_wq don't need WQ_MEM_RECLAIM Tejun Heo
2011-01-03 13:49 ` [PATCH 07/32] cpufreq: use system_wq instead of dedicated workqueues Tejun Heo
2011-01-03 13:49 ` [PATCH 08/32] drm/nouveau: use system_wq instead of dev_priv->wq Tejun Heo
2011-01-03 13:49   ` Tejun Heo
2011-01-05  1:07   ` Ben Skeggs
2011-01-05  1:16     ` Ben Skeggs
2011-01-06 17:29       ` Tejun Heo
2011-01-26 16:49         ` [PATCH UPDATED " Tejun Heo
2011-02-01 10:41           ` Tejun Heo
2011-02-04  1:53             ` Ben Skeggs
2011-02-04 11:03               ` Tejun Heo
2011-01-03 13:49 ` [PATCH 09/32] drm/radeon: " Tejun Heo
2011-01-03 13:49   ` Tejun Heo
2011-01-05  0:21   ` Alex Deucher
2011-01-06  4:31     ` Dave Airlie
2011-01-03 13:49 ` [PATCH 10/32] input/tps6507x-ts: use system_wq instead of dedicated workqueue Tejun Heo
2011-01-03 14:39   ` Dan Carpenter
2011-01-03 16:34     ` Todd Fischer
2011-01-25 14:19       ` Tejun Heo
2011-01-25 16:13         ` Todd Fischer
2011-01-25 16:50           ` Dmitry Torokhov
2011-01-26 10:43             ` Tejun Heo
2011-01-03 13:49 ` [PATCH 11/32] v4l/cx18: update workqueue usage Tejun Heo
2011-01-04  0:54   ` Andy Walls
2011-01-04  8:36     ` Tejun Heo
2011-01-04 13:21       ` Andy Walls
2011-01-08 17:03   ` Andy Walls
2011-01-03 13:49 ` [PATCH 12/32] i2o: use alloc_workqueue() instead of create_workqueue() Tejun Heo
2011-01-03 13:49 ` [PATCH 13/32] misc/iwmc3200top: use system_wq instead of dedicated workqueues Tejun Heo
2011-01-03 13:49 ` [PATCH 14/32] wireless/ipw2x00: " Tejun Heo
2011-01-06 20:51   ` John W. Linville
2011-01-03 13:49 ` [PATCH 15/32] wireless/libertas[_tf]: " Tejun Heo
2011-02-01 10:52   ` Tejun Heo
2011-01-03 13:49 ` [PATCH 16/32] scsi/be2iscsi,qla2xxx: convert to alloc_workqueue() Tejun Heo
2011-02-01 23:45   ` Mike Christie
2011-02-02 10:25     ` Tejun Heo
2011-02-02 20:41       ` Mike Christie
2011-02-03  9:31         ` Tejun Heo
2011-01-03 13:49 ` [PATCH 17/32] scsi/ibmvstgt: use system_wq instead of vtgtd workqueue Tejun Heo
2011-01-03 17:45   ` Bart Van Assche
2011-01-04  5:20     ` Tejun Heo
2011-01-24 16:09   ` Bart Van Assche
2011-01-24 16:24     ` Tejun Heo
2011-02-01 10:40       ` Tejun Heo [this message]
2011-02-01 14:18         ` FUJITA Tomonori
2011-02-01 14:25           ` James Bottomley
2011-02-01 14:29           ` Tejun Heo
2011-01-03 13:49 ` [PATCH 18/32] scsi/scsi_tgt_lib: scsi_tgtd isn't used in memory reclaim path Tejun Heo
2011-01-03 13:49 ` [PATCH 19/32] usb/ueagle-atm: use system_wq instead of dedicated workqueues Tejun Heo
2011-01-03 13:49 ` [PATCH 20/32] video/msm_fb: " Tejun Heo
     [not found]   ` <1294062595-30097-21-git-send-email-tj-DgEjT+Ai2ygdnm+yROfE0A@public.gmane.org>
2011-01-03 17:06     ` Stanislaw Gruszka
2011-01-03 17:06       ` Stanislaw Gruszka
     [not found]       ` <20110103170615.GB2285-H+wXaHxf7aLQT0dZR+AlfA@public.gmane.org>
2011-01-03 18:10         ` Daniel Walker
2011-01-03 18:10           ` Daniel Walker
     [not found]           ` <1294078245.18295.5.camel-y5Owza0q8UhBVvN7MMdr1KRtKmQZhJ7pQQ4Iyu8u01E@public.gmane.org>
2011-01-25 13:45             ` Tejun Heo
2011-01-25 13:45               ` Tejun Heo
     [not found]               ` <20110125134558.GY27510-Gd/HAXX7CRxy/B6EtB590w@public.gmane.org>
2011-01-25 18:00                 ` Daniel Walker
2011-01-25 18:00                   ` Daniel Walker
2011-01-25 19:14                   ` David Brown
2011-01-25 19:16                     ` Daniel Walker
     [not found]                       ` <1295982976.25496.29.camel-y5Owza0q8UhBVvN7MMdr1KRtKmQZhJ7pQQ4Iyu8u01E@public.gmane.org>
2011-01-25 22:08                         ` Carl Vanderlip
2011-01-25 22:08                           ` Carl Vanderlip
2011-01-25 23:21   ` David Brown
2011-01-26 10:41     ` Tejun Heo
2011-01-26 18:04       ` David Brown
2011-01-03 13:49 ` [PATCH 21/32] fs/aio: aio_wq isn't used in memory reclaim path Tejun Heo
2011-01-04 15:56   ` Jeff Moyer
2011-01-05 11:28     ` Tejun Heo
2011-01-05 14:50       ` Jeff Moyer
2011-01-05 15:00         ` Benjamin LaHaise
2011-01-05 15:49           ` Jeff Moyer
2011-01-26 11:21   ` [PATCH UPDATED " Tejun Heo
2011-01-26 16:29     ` Jeff Moyer
2011-01-26 16:38       ` Tejun Heo
2011-01-03 13:49 ` [PATCH 22/32] ceph: fsc->*_wq's aren't " Tejun Heo
2011-01-03 17:58   ` Sage Weil
2011-01-03 13:49 ` [PATCH 23/32] net/ceph: make ceph_msgr_wq non-reentrant Tejun Heo
2011-01-03 17:58   ` Sage Weil
2011-01-03 13:49 ` [PATCH 24/32] dlm: dlm workqueues aren't used in memory reclaim path Tejun Heo
2011-01-03 13:58   ` Steven Whitehouse
2011-01-03 13:58     ` [Cluster-devel] " Steven Whitehouse
2011-01-03 14:01     ` Tejun Heo
2011-01-03 14:21       ` Steven Whitehouse
2011-01-03 14:21         ` [Cluster-devel] " Steven Whitehouse
2011-01-03 14:27         ` Tejun Heo
2011-01-03 14:39           ` Steven Whitehouse
2011-01-03 14:39             ` [Cluster-devel] " Steven Whitehouse
2011-01-03 14:44             ` Tejun Heo
2011-01-03 13:49 ` [PATCH 25/32] ext4: convert to alloc_workqueue() Tejun Heo
2011-01-03 13:49 ` [PATCH 26/32] ocfs2: use system_wq instead of ocfs2_quota_wq Tejun Heo
2011-01-03 13:49 ` [PATCH 27/32] reiserfs: make commit_wq use the default concurrency level Tejun Heo
2011-01-03 13:49 ` [PATCH 28/32] xfs: convert to alloc_workqueue() Tejun Heo
2011-01-03 13:49 ` [PATCH 29/32] net/9p: use system_wq instead of p9_mux_wq Tejun Heo
2011-01-03 13:49 ` [PATCH 30/32] net/9p: replace p9_poll_task with a work Tejun Heo
2011-01-03 13:49 ` [PATCH 31/32] rds/ib: use system_wq instead of rds_ib_fmr_wq Tejun Heo
2011-01-03 13:49 ` [PATCH 32/32] rxrpc: rxrpc_workqueue isn't used during memory reclaim Tejun Heo
2011-01-25 14:29 ` [PATCHSET] workqueue: update workqueue users - replace create_workqueue() Tejun Heo
2011-01-25 16:26   ` Dave Jones
2011-01-26 10:40     ` Tejun Heo
2011-01-25 17:47   ` Madhu Iyengar
2011-01-26  4:46   ` Greg KH
2011-02-01 10:44   ` Tejun Heo

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