From: fche@redhat.com (Frank Ch. Eigler)
To: Steven Rostedt <rostedt@goodmis.org>
Cc: Ingo Molnar <mingo@elte.hu>, LKML <linux-kernel@vger.kernel.org>,
RT <linux-rt-users@vger.kernel.org>,
Thomas Gleixner <tglx@linutronix.de>,
john stultz <johnstul@us.ibm.com>
Subject: Re: [PATCH RT 3/3 - take two ] fix get_monotonic_cycles for latency tracer
Date: Sat, 25 Aug 2007 07:06:54 -0400 [thread overview]
Message-ID: <y0modgv50vl.fsf@ton.toronto.redhat.com> (raw)
In-Reply-To: <1187982149.4574.1.camel@localhost.localdomain> (Steven Rostedt's message of "Fri, 24 Aug 2007 15:02:29 -0400")
Steven Rostedt <rostedt@goodmis.org> writes:
> [...]
> + * [...] We don't need to grab
> + * any locks, we just keep trying until get all the
> + * calculations together in one state.
> + *
> + * In fact, we __cant__ grab any locks. This
> + * function is called from the latency_tracer which can
> + * be called anywhere. To grab any locks (including
> + * seq_locks) we risk putting ourselves into a deadlock.
Perhaps you could add a comment about why the loop, which appears
potentially infinite as written, avoids livelock. (It looks rather
like a seqlock read loop.)
- FChE
next prev parent reply other threads:[~2007-08-25 11:07 UTC|newest]
Thread overview: 6+ messages / expand[flat|nested] mbox.gz Atom feed top
2007-08-24 17:57 [PATCH RT 3/3] fix get_monotonic_cycles for latency tracer Steven Rostedt
2007-08-24 18:30 ` john stultz
2007-08-24 18:56 ` Steven Rostedt
2007-08-24 19:02 ` [PATCH RT 3/3 - take two ] " Steven Rostedt
2007-08-25 11:06 ` Frank Ch. Eigler [this message]
2007-08-26 1:26 ` Steven Rostedt
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