From: James Bottomley <James.Bottomley@suse.de>
To: FUJITA Tomonori <fujita.tomonori@lab.ntt.co.jp>
Cc: tj@kernel.org, bvanassche@acm.org, linux-kernel@vger.kernel.org,
linux-scsi@vger.kernel.org, brking@linux.vnet.ibm.com,
rcj@linux.vnet.ibm.com
Subject: Re: [PATCH 17/32] scsi/ibmvstgt: use system_wq instead of vtgtd workqueue
Date: Tue, 01 Feb 2011 08:25:32 -0600 [thread overview]
Message-ID: <1296570332.3049.8.camel@mulgrave.site> (raw)
In-Reply-To: <20110201231836D.fujita.tomonori@lab.ntt.co.jp>
On Tue, 2011-02-01 at 23:18 +0900, FUJITA Tomonori wrote:
> On Tue, 1 Feb 2011 11:40:43 +0100
> Tejun Heo <tj@kernel.org> wrote:
>
> > 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?
>
> FYI, this driver will be replaced shortly. Now I have the working
> ibmvscsis driver for the new target framework. I'll submit it this
> week. So this driver will be removed soon or later (if James prefer to
> go through the proper Documentation/feature-removal-schedule.txt
> process, it'll be for some time). You could leave this alone, I guess.
Whatever works for you is fine by me. I don't think we need to go
through feature removal since we're not technically removing the
feature.
James
next prev parent reply other threads:[~2011-02-01 14:25 UTC|newest]
Thread overview: 104+ 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 15:37 ` 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 ` [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
2011-01-04 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
2011-01-05 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
2011-01-05 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
2011-02-01 14:18 ` FUJITA Tomonori
2011-02-01 14:25 ` James Bottomley [this message]
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
2011-01-03 17:06 ` Stanislaw Gruszka
2011-01-03 18:10 ` Daniel Walker
2011-01-25 13:45 ` Tejun Heo
2011-01-25 18:00 ` Daniel Walker
2011-01-25 19:14 ` David Brown
2011-01-25 19:16 ` Daniel Walker
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 14:01 ` Tejun Heo
2011-01-03 14:21 ` Steven Whitehouse
2011-01-03 14:27 ` Tejun Heo
2011-01-03 14:39 ` 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
2011-01-26 4:46 ` Greg KH
2011-02-01 10:44 ` Tejun Heo
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