From: Rik van Riel <riel@redhat.com>
To: Manfred Spraul <manfred@colorfullife.com>
Cc: LKML <linux-kernel@vger.kernel.org>,
Andrew Morton <akpm@linux-foundation.org>,
Davidlohr Bueso <davidlohr.bueso@hp.com>,
hhuang@redhat.com, Linus Torvalds <torvalds@linux-foundation.org>
Subject: Re: [PATCH 3/4] ipc/sem.c: Always use only one queue for alter operations.
Date: Mon, 27 May 2013 14:00:03 -0400 [thread overview]
Message-ID: <51A39F23.2080507@redhat.com> (raw)
In-Reply-To: <1369559335-13491-4-git-send-email-manfred@colorfullife.com>
On 05/26/2013 05:08 AM, Manfred Spraul wrote:
> There are two places that can contain alter operations:
> - the global queue: sma->pending_alter
> - the per-semaphore queues: sma->sem_base[].pending_alter.
>
> Since one of the queues must be processed first, this causes an odd
> priorization of the wakeups:
> Right now, complex operations have priority over simple ops.
>
> The patch restores the behavior of linux <=3.0.9: The longest
> waiting operation has the highest priority.
>
> This is done by using only one queue:
> - if there are complex ops, then sma->pending_alter is used.
> - otherwise, the per-semaphore queues are used.
>
> As a side effect, do_smart_update_queue() becomes much simpler:
> No more goto logic.
>
> Signed-off-by: Manfred Spraul <manfred@colorfullife.com>
This is the one where I really wonder whether the
complexity is warranted.
Again, the code does look correct.
Acked-by: Rik van Riel <riel@redhat.com>
next prev parent reply other threads:[~2013-05-27 18:24 UTC|newest]
Thread overview: 23+ messages / expand[flat|nested] mbox.gz Atom feed top
2013-05-26 9:08 [PATCH 0/4] ipc/sem.c: Bug fixes, regression fixes, v3 Manfred Spraul
2013-05-26 9:08 ` [PATCH 1/4] ipc/sem.c: Fix missing wakeups in do_smart_update_queue() Manfred Spraul
2013-05-27 17:51 ` Rik van Riel
2013-05-27 19:53 ` Manfred Spraul
2013-05-26 9:08 ` [PATCH 2/4] ipc/sem: seperate wait-for-zero and alter tasks into seperate queues Manfred Spraul
2013-05-27 17:57 ` Rik van Riel
2013-06-01 9:20 ` Manfred Spraul
2013-06-01 10:03 ` Mike Galbraith
2013-06-01 10:05 ` Mike Galbraith
2013-06-01 11:04 ` Mike Galbraith
2013-06-01 11:52 ` Manfred Spraul
2013-05-26 9:08 ` [PATCH 3/4] ipc/sem.c: Always use only one queue for alter operations Manfred Spraul
2013-05-27 18:00 ` Rik van Riel [this message]
2013-05-26 9:08 ` [PATCH 4/4] ipc/sem.c: Rename try_atomic_semop() to perform_atomic_semop(), docu update Manfred Spraul
2013-05-27 17:59 ` Rik van Riel
2013-05-26 17:37 ` [PATCH 0/4] ipc/sem.c: Bug fixes, regression fixes, v3 Linus Torvalds
2013-05-26 20:50 ` Davidlohr Bueso
2013-05-26 22:59 ` Linus Torvalds
2013-05-27 15:57 ` Manfred Spraul
2013-05-28 20:37 ` Davidlohr Bueso
2013-05-27 2:04 ` Greg KH
2013-05-27 17:50 ` Rik van Riel
2013-05-27 19:57 ` Greg KH
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