From: Peter Zijlstra <peterz@infradead.org>
To: Oleg Nesterov <oleg@redhat.com>
Cc: Will Deacon <will.deacon@kernel.org>,
Ingo Molnar <mingo@kernel.org>,
Thomas Gleixner <tglx@linutronix.de>,
linux-kernel@vger.kernel.org, bigeasy@linutronix.de,
juri.lelli@redhat.com, williams@redhat.com, bristot@redhat.com,
longman@redhat.com, dave@stgolabs.net, jack@suse.com
Subject: Re: [PATCH] locking/percpu_rwsem: Rewrite to not use rwsem
Date: Tue, 6 Aug 2019 19:15:15 +0200 [thread overview]
Message-ID: <20190806171515.GR2349@hirez.programming.kicks-ass.net> (raw)
In-Reply-To: <20190806161741.GC21454@redhat.com>
On Tue, Aug 06, 2019 at 06:17:42PM +0200, Oleg Nesterov wrote:
> but this will also wake all the pending readers up. Every reader will burn
> CPU for no reason and likely delay the writer.
>
> In fact I'm afraid this can lead to live-lock, because every reader in turn
> will call __percpu_up_read().
I didn't really consider that case important; because of how heavy the
write side is, it should be relatively rare.
> How about 2 wait queues?
That said, I can certainly try that.
next prev parent reply other threads:[~2019-08-06 17:15 UTC|newest]
Thread overview: 19+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-08-05 14:02 Peter Zijlstra
2019-08-05 14:43 ` Boqun Feng
2019-08-05 14:58 ` Boqun Feng
2019-08-05 15:43 ` Peter Zijlstra
2019-08-06 14:15 ` Boqun Feng
2019-08-06 16:17 ` Oleg Nesterov
2019-08-06 17:15 ` Peter Zijlstra [this message]
2019-08-07 9:56 ` Oleg Nesterov
2019-10-29 18:47 ` Peter Zijlstra
2019-10-30 14:21 ` Oleg Nesterov
2019-10-30 16:09 ` Peter Zijlstra
2019-10-30 17:52 ` Peter Zijlstra
2019-10-30 18:47 ` Peter Zijlstra
2019-10-30 19:31 ` Peter Zijlstra
2019-10-31 6:11 ` Peter Zijlstra
2019-08-07 14:45 ` Will Deacon
2019-10-29 19:06 ` Peter Zijlstra
2019-10-30 15:57 ` Oleg Nesterov
2019-10-30 16:47 ` Peter Zijlstra
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