From: Karim Yaghmour <karim.yaghmour@opersys.com>
To: Andi Kleen <andi@firstfloor.org>
Cc: linux-kernel@vger.kernel.org,
Steven Rostedt <rostedt@goodmis.org>,
mingo@elte.hu
Subject: Re: Reading perf counters at ftrace trace boundaries
Date: Sun, 11 Aug 2013 22:39:00 -0300 [thread overview]
Message-ID: <52083CB4.2030308@opersys.com> (raw)
In-Reply-To: <87haevog75.fsf@tassilo.jf.intel.com>
On 13-08-11 10:23 PM, Andi Kleen wrote:
> KVM does it, see arch/x86/kvm/pmu.c. Essentially it would be doing RDPMC.
Thx for the pointer, appreciated.
> But the overhead will be likely very high, some sampling approach
> is likely better.
Indeed. It doesn't actually have to be at every single ftrace
begin/exit. But possibly starting with some kind of every nth and then
drilling down as the culprit is incrementally singled-out.
--
Karim Yaghmour
CEO - Opersys inc. / www.opersys.com
http://twitter.com/karimyaghmour
next prev parent reply other threads:[~2013-08-12 1:39 UTC|newest]
Thread overview: 8+ messages / expand[flat|nested] mbox.gz Atom feed top
2013-08-12 0:03 Reading perf counters at ftrace trace boundaries Karim Yaghmour
2013-08-12 1:23 ` Andi Kleen
2013-08-12 1:39 ` Karim Yaghmour [this message]
2013-08-12 1:47 ` Andi Kleen
2013-08-12 1:59 ` Karim Yaghmour
2013-08-12 2:24 ` zhangwei(Jovi)
2013-08-12 15:26 ` Karim Yaghmour
2013-08-13 7:12 ` zhangwei(Jovi)
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