From: Waiman Long <longman@redhat.com>
To: Peter Zijlstra <peterz@infradead.org>
Cc: "Hillf Danton" <hdanton@sina.com>, 马振华 <mazhenhua@xiaomi.com>,
mingo <mingo@redhat.com>, will <will@kernel.org>,
"boqun.feng" <boqun.feng@gmail.com>,
linux-kernel <linux-kernel@vger.kernel.org>
Subject: Re: [BUG]locking/rwsem: only clean RWSEM_FLAG_HANDOFF when already set
Date: Thu, 11 Nov 2021 14:52:19 -0500 [thread overview]
Message-ID: <cd5e96e6-fbfd-487a-e308-13800c79ead3@redhat.com> (raw)
In-Reply-To: <e16f9fc2-ce01-192b-065d-460c2ad9b317@redhat.com>
On 11/11/21 14:36, Waiman Long wrote:
>
> On 11/11/21 14:20, Peter Zijlstra wrote:
>> On Thu, Nov 11, 2021 at 02:14:48PM -0500, Waiman Long wrote:
>>> As for the PHASE_CHANGE name, we have to be consistent in both rwsem
>>> and
>>> mutex. Maybe a follow up patch if you think we should change the
>>> terminology.
>> Well, that's exactly the point, they do radically different things.
>> Having the same name for two different things is confusing.
>>
>> Anyway, let me go read that patch you sent.
>
> My understanding of handoff is to disable optimistic spinning to let
> waiters in the wait queue have an opportunity to acquire the lock.
> There are difference in details on how to do that in mutex and rwsem,
> though.
>
> BTW, I have decided that we should further simply the trylock for loop
> in rwsem_down_write_slowpath() to make it easier to read. That is the
> only difference in the attached v2 patch compared with the previous one.
My bad, I forgot to initialize waiter.handoff_set in
rwsem_down_write_slowpath(). I will send out an updated version once you
have finished your review.
Cheers,
Longman
next prev parent reply other threads:[~2021-11-11 19:52 UTC|newest]
Thread overview: 26+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <4fafad133b074f279dbab1aa3642e23f@xiaomi.com>
2021-11-07 3:25 ` [BUG]locking/rwsem: only clean RWSEM_FLAG_HANDOFF when already set Waiman Long
2021-11-07 3:28 ` Waiman Long
[not found] ` <20211107090131.1535-1-hdanton@sina.com>
2021-11-07 15:24 ` Waiman Long
2021-11-07 19:52 ` Waiman Long
2021-11-10 21:38 ` Peter Zijlstra
2021-11-11 2:42 ` Maria Yu
2021-11-11 15:08 ` Peter Zijlstra
2021-11-11 19:14 ` Waiman Long
2021-11-11 19:20 ` Peter Zijlstra
2021-11-11 19:36 ` Waiman Long
2021-11-11 19:52 ` Waiman Long [this message]
2021-11-11 20:26 ` Peter Zijlstra
2021-11-11 21:01 ` Waiman Long
2021-11-11 21:25 ` Waiman Long
2021-11-11 21:53 ` Peter Zijlstra
2021-11-11 21:55 ` Waiman Long
2021-11-11 22:00 ` Waiman Long
2021-11-11 21:38 ` Peter Zijlstra
2021-11-11 21:46 ` Waiman Long
2021-11-11 20:35 ` Peter Zijlstra
2021-11-11 20:39 ` Peter Zijlstra
2021-11-11 20:45 ` Waiman Long
2021-11-11 21:27 ` Peter Zijlstra
2021-11-11 21:54 ` Waiman Long
2021-11-11 20:50 ` Peter Zijlstra
2021-11-11 21:09 ` Waiman Long
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