From: Josh Triplett <josht@linux.vnet.ibm.com>
To: paulmck@linux.vnet.ibm.com
Cc: linux-rt-users@vger.kernel.org, linux-kernel@vger.kernel.org,
mingo@elte.hu, dipankar@in.ibm.com, ego@in.ibm.com,
vatsa@in.ibm.com
Subject: Re: [PATCH RFC -rt] Allow rcutorture to handle synchronize_sched()
Date: Fri, 03 Aug 2007 15:38:32 -0700 [thread overview]
Message-ID: <1186180712.2677.16.camel@josh-work.beaverton.ibm.com> (raw)
In-Reply-To: <20070803184449.GA2196@linux.vnet.ibm.com>
On Fri, 2007-08-03 at 11:44 -0700, Paul E. McKenney wrote:
> The rcutorture module uses a random-number generator that periodically
> calls get_random_bytes() to add entropy. This random-number generator
> is invoked from within the RCU read-side critical section, which, in the
> case of the synchronize_sched() variant of RCU, has preeemption disabled.
> Unfortunately, get_random_bytes() ends up acquiring normal spinlocks,
> which can block in -rt, resulting in very large numbers of "scheduling
> while atomic" messages.
>
> This patch takes a very crude approach, simply substituting the time
> of day for get_random_bytes().
>
> Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Acked-by: Josh Triplett <josh@kernel.org>
prev parent reply other threads:[~2007-08-03 22:38 UTC|newest]
Thread overview: 2+ messages / expand[flat|nested] mbox.gz Atom feed top
2007-08-03 18:44 Paul E. McKenney
2007-08-03 22:38 ` Josh Triplett [this message]
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