From: Paolo Bonzini <pbonzini@redhat.com>
To: Wen Congyang <wency@cn.fujitsu.com>, qemu-devl <qemu-devel@nongnu.org>
Subject: Re: [Qemu-devel] [PATCH v2 for-2.5] rcu: Allow calling rcu_(un)register_thread() during synchronize_rcu()
Date: Tue, 28 Jul 2015 12:18:00 +0200 [thread overview]
Message-ID: <55B756D8.9090503@redhat.com> (raw)
In-Reply-To: <55B7532D.9010506@cn.fujitsu.com>
On 28/07/2015 12:02, Wen Congyang wrote:
> I have a question about rcu: while do we call wait_for_readers()
> twice for 32-bit host?
Because there is a very small but non-zero probability of the counter
going up by exactly 2^31 periods (periods are stored in bits 1-31 so you
lose one bit) while the thread is sleeping. This detail of the
implementation comes from URCU.
Paolo
next prev parent reply other threads:[~2015-07-28 10:18 UTC|newest]
Thread overview: 9+ messages / expand[flat|nested] mbox.gz Atom feed top
2015-07-28 2:26 [Qemu-devel] [PATCH v2 for-2.5] rcu: Allow calling rcu_(un)register_thread() during synchronize_rcu() Wen Congyang
2015-07-28 9:59 ` Paolo Bonzini
2015-07-28 10:02 ` Wen Congyang
2015-07-28 10:18 ` Paolo Bonzini [this message]
2015-07-28 10:33 ` Wen Congyang
2015-07-28 11:46 ` Paolo Bonzini
2015-07-28 13:29 ` Wen Congyang
2015-07-28 16:14 ` Paolo Bonzini
2015-07-29 1:11 ` Wen Congyang
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