From: Mike Galbraith <efault@gmx.de>
To: paulmck@linux.vnet.ibm.com
Cc: linux-kernel@vger.kernel.org, mingo@elte.hu,
laijs@cn.fujitsu.com, dipankar@in.ibm.com,
akpm@linux-foundation.org, mathieu.desnoyers@efficios.com,
josh@joshtriplett.org, niv@us.ibm.com, tglx@linutronix.de,
peterz@infradead.org, rostedt@goodmis.org,
Valdis.Kletnieks@vt.edu, dhowells@redhat.com,
eric.dumazet@gmail.com, darren@dvhart.com, fweisbec@gmail.com,
sivanich@sgi.com
Subject: Re: [PATCH RFC] rcu: Permit limiting of force_quiescent_state() latency
Date: Mon, 19 Mar 2012 04:47:12 +0100 [thread overview]
Message-ID: <1332128832.7283.34.camel@marge.simpson.net> (raw)
In-Reply-To: <20120319001014.GD2393@linux.vnet.ibm.com>
On Sun, 2012-03-18 at 17:10 -0700, Paul E. McKenney wrote:
> Thank you very much for your efforts on this!!!
No problem, irq holdoff troubles are worth effort.
> Given that you were seeing about 200-microsecond latency spikes on
> grace-period initialization, I would expect that you would need about
> 200 dyntick-idle CPUs for force_quiescent_state() to give you a
> ten-microsecond spike, so I am not surprised that you could not see
> the difference on 60 CPUs, which probably have given you something
> like 3 microseconds..
Crawling over fewer locks should still save cycles, so I'll measure.
Big box rt needs every little usec we can scrape together.
-Mike
prev parent reply other threads:[~2012-03-19 3:47 UTC|newest]
Thread overview: 6+ messages / expand[flat|nested] mbox.gz Atom feed top
2012-03-16 16:03 Paul E. McKenney
2012-03-17 16:57 ` Mike Galbraith
2012-03-18 7:19 ` Mike Galbraith
2012-03-18 15:00 ` Mike Galbraith
2012-03-19 0:10 ` Paul E. McKenney
2012-03-19 3:47 ` Mike Galbraith [this message]
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