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From: Tejun Heo <tj@kernel.org>
To: Mandeep Singh Baines <msb@chromium.org>
Cc: Steffen Klassert <steffen.klassert@secunet.com>,
	Will Drewry <wad@chromium.org>,
	Rusty Russell <rusty@rustcorp.com.au>,
	linux-kernel@vger.kernel.org, dm-devel@redhat.com,
	Elly Jones <ellyjones@chromium.org>,
	Mikulas Patocka <mpatocka@redhat.com>,
	Andrew Morton <akpm@linux-foundation.org>,
	Olof Johansson <olofj@chromium.org>,
	Alasdair G Kergon <agk@redhat.com>, Milan Broz <mbroz@redhat.com>
Subject: Re: workqueues and percpu (was: [PATCH] dm: remake of the verity target)
Date: Tue, 14 Aug 2012 10:54:31 -0700	[thread overview]
Message-ID: <20120814175431.GR25632@google.com> (raw)
In-Reply-To: <20120309220623.GM27051@google.com>

Hello,

On Fri, Mar 09, 2012 at 02:06:23PM -0800, Mandeep Singh Baines wrote:
> > I think the right thing to do for now is to add cpu hotplug notifier
> > and do flush_work_sync() on the work item.  We can later move that
> > logic into workqueue and remove it from crypto.
> > 
> 
> That seems like the correct solution. I will implement that.

So, I've been looking at it and now am not so sure whether moving it
to workqueue core is necessary.  With the proposed workqueue updates,
workqueue's behavior is now closely aligned with the timer which also
considers the specified affinity overridable (to avoid reentrancy and
during CPU offlining) and I don't think it's reasonable to require
users which need strict affinity to implement proper CPU up/down
notifiers - in many cases, they need them anyway.  I'll try to review
the current users and think more about it.

Thanks.

-- 
tejun

WARNING: multiple messages have this Message-ID (diff)
From: Tejun Heo <tj@kernel.org>
To: Mandeep Singh Baines <msb@chromium.org>
Cc: Andrew Morton <akpm@linux-foundation.org>,
	Mikulas Patocka <mpatocka@redhat.com>,
	linux-kernel@vger.kernel.org, dm-devel@redhat.com,
	Alasdair G Kergon <agk@redhat.com>,
	Will Drewry <wad@chromium.org>,
	Elly Jones <ellyjones@chromium.org>,
	Milan Broz <mbroz@redhat.com>,
	Olof Johansson <olofj@chromium.org>,
	Steffen Klassert <steffen.klassert@secunet.com>,
	Rusty Russell <rusty@rustcorp.com.au>
Subject: Re: workqueues and percpu (was: [PATCH] dm: remake of the verity target)
Date: Tue, 14 Aug 2012 10:54:31 -0700	[thread overview]
Message-ID: <20120814175431.GR25632@google.com> (raw)
In-Reply-To: <20120309220623.GM27051@google.com>

Hello,

On Fri, Mar 09, 2012 at 02:06:23PM -0800, Mandeep Singh Baines wrote:
> > I think the right thing to do for now is to add cpu hotplug notifier
> > and do flush_work_sync() on the work item.  We can later move that
> > logic into workqueue and remove it from crypto.
> > 
> 
> That seems like the correct solution. I will implement that.

So, I've been looking at it and now am not so sure whether moving it
to workqueue core is necessary.  With the proposed workqueue updates,
workqueue's behavior is now closely aligned with the timer which also
considers the specified affinity overridable (to avoid reentrancy and
during CPU offlining) and I don't think it's reasonable to require
users which need strict affinity to implement proper CPU up/down
notifiers - in many cases, they need them anyway.  I'll try to review
the current users and think more about it.

Thanks.

-- 
tejun

  reply	other threads:[~2012-08-14 17:54 UTC|newest]

Thread overview: 38+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2012-03-02  0:33 [PATCH] dm: verity target Mandeep Singh Baines
2012-03-02 16:08 ` Mandeep Singh Baines
2012-03-02 16:08   ` Mandeep Singh Baines
2012-03-04 19:18 ` [PATCH] dm: remake of the " Mikulas Patocka
2012-03-04 19:35   ` userspace hashing utility for dm-verity Mikulas Patocka
2012-03-06 21:59   ` [PATCH] dm: remake of the verity target Mandeep Singh Baines
2012-03-08 22:21     ` workqueues and percpu (was: [PATCH] dm: remake of the verity target) Mikulas Patocka
2012-03-08 22:39       ` Andrew Morton
2012-03-08 23:15         ` Tejun Heo
2012-03-08 23:30           ` Andrew Morton
2012-03-09  0:33             ` Tejun Heo
2012-03-09  0:51               ` Tejun Heo
2012-03-09 21:15           ` Mandeep Singh Baines
2012-03-09 21:20             ` Tejun Heo
2012-03-09 22:06               ` Mandeep Singh Baines
2012-08-14 17:54                 ` Tejun Heo [this message]
2012-08-14 17:54                   ` Tejun Heo
2012-03-13 22:20     ` [PATCH] dm: remake of the verity target Mikulas Patocka
2012-03-14 21:13       ` Will Drewry
2012-03-17  1:16         ` Mikulas Patocka
2012-03-17  3:06           ` Will Drewry
2012-03-14 21:43       ` Mandeep Singh Baines
2012-03-20 15:41       ` Mandeep Singh Baines
2012-03-21  0:54         ` Mikulas Patocka
2012-03-21  3:03           ` Mandeep Singh Baines
2012-03-21  3:11           ` [dm-devel] " Mikulas Patocka
2012-03-21  3:30             ` Mandeep Singh Baines
2012-03-21  3:44               ` Mikulas Patocka
2012-03-21  3:49                 ` Mandeep Singh Baines
2012-03-21 17:08                   ` Mikulas Patocka
2012-03-21 17:08                     ` [dm-devel] " Mikulas Patocka
2012-03-21 17:09                     ` Mikulas Patocka
2012-03-21 17:09                       ` [dm-devel] " Mikulas Patocka
2012-03-22 17:41                     ` Mandeep Singh Baines
2012-03-22 21:52                       ` Mikulas Patocka
2012-03-23  3:15                         ` Mandeep Singh Baines
2012-03-24  3:48                           ` Mikulas Patocka
2012-03-21  1:10         ` Mikulas Patocka

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