From: Arjan van de Ven <arjan@linux.intel.com>
To: paulmck@linux.vnet.ibm.com
Cc: Peter Zijlstra <peterz@infradead.org>,
linux-kernel@vger.kernel.org, mingo@kernel.org,
laijs@cn.fujitsu.com, dipankar@in.ibm.com,
akpm@linux-foundation.org, mathieu.desnoyers@efficios.com,
josh@joshtriplett.org, tglx@linutronix.de, rostedt@goodmis.org,
dhowells@redhat.com, edumazet@google.com, dvhart@linux.intel.com,
fweisbec@gmail.com, oleg@redhat.com, bobby.prani@gmail.com
Subject: Re: [PATCH tip/core/rcu 0/4] Programmatic nestable expedited grace periods
Date: Sat, 21 Feb 2015 07:51:34 -0800 [thread overview]
Message-ID: <54E8A986.4090302@linux.intel.com> (raw)
In-Reply-To: <20150220182745.GN5745@linux.vnet.ibm.com>
>>
>> there's a few others as well that I'm chasing down...
>> .. but the flip side, prior to running ring 3 code, why NOT do fast expedites?
>
> It would be good to have before-and-after measurements of actual
> boot time. Are these numbers available?
To show the boot time, I'm using the timestamp of the "Write protecting" line,
that's pretty much the last thing we print prior to ring 3 execution.
A kernel with default RCU behavior (inside KVM, only virtual devices) looks like this:
[ 0.038724] Write protecting the kernel read-only data: 10240k
a kernel with expedited RCU (using the command line option, so that I don't have
to recompile between measurements and thus am completely oranges-to-oranges)
[ 0.031768] Write protecting the kernel read-only data: 10240k
which, in percentage, is an 18% improvement.
next prev parent reply other threads:[~2015-02-21 15:51 UTC|newest]
Thread overview: 29+ messages / expand[flat|nested] mbox.gz Atom feed top
2015-02-20 5:08 [PATCH tip/core/rcu 0/4] Programmatic nestable expedited grace periods Paul E. McKenney
2015-02-20 5:09 ` [PATCH v2 RFC tip/core/rcu 1/4] rcu: Provide rcu_expedite_gp() and rcu_unexpedite_gp() Paul E. McKenney
2015-02-20 5:09 ` [PATCH v2 RFC tip/core/rcu 2/4] rcu: Add rcu_expedite_gp() and rcu_unexpedite_gp() to rcutorture Paul E. McKenney
2015-02-20 5:09 ` [PATCH v2 RFC tip/core/rcu 3/4] rcu: Update from rcu_expedited variable to rcu_gp_is_expedited() Paul E. McKenney
2015-02-20 5:09 ` [PATCH v2 RFC tip/core/rcu 4/4] rcu: Add Kconfig option to expedite grace periods during boot Paul E. McKenney
2015-02-20 9:11 ` [PATCH tip/core/rcu 0/4] Programmatic nestable expedited grace periods Peter Zijlstra
2015-02-20 16:37 ` Paul E. McKenney
2015-02-20 16:54 ` Peter Zijlstra
2015-02-20 17:14 ` Paul E. McKenney
2015-02-20 17:32 ` Arjan van de Ven
2015-02-20 17:43 ` Peter Zijlstra
2015-02-20 17:45 ` Arjan van de Ven
2015-02-21 16:08 ` Peter Zijlstra
2015-02-22 1:43 ` Paul E. McKenney
2015-02-20 18:38 ` Paul E. McKenney
2015-02-21 16:11 ` Peter Zijlstra
2015-02-21 17:59 ` Paul E. McKenney
2015-02-20 18:27 ` Paul E. McKenney
2015-02-20 18:29 ` Arjan van de Ven
2015-02-20 18:39 ` Paul E. McKenney
2015-02-21 15:51 ` Arjan van de Ven [this message]
2015-02-21 18:00 ` Paul E. McKenney
2015-02-22 3:58 ` Josh Triplett
2015-02-22 6:10 ` Paul E. McKenney
2015-02-22 18:31 ` Arjan van de Ven
2015-02-22 18:48 ` Josh Triplett
2015-02-21 6:04 ` Josh Triplett
2015-02-21 15:12 ` Mathieu Desnoyers
2015-02-21 23:58 ` Paul E. McKenney
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