From: Andi Kleen <ak@linux.intel.com>
To: Alexander Gordeev <agordeev@redhat.com>
Cc: linux-kernel@vger.kernel.org,
Arnaldo Carvalho de Melo <acme@ghostprotocols.net>,
Jiri Olsa <jolsa@redhat.com>, Ingo Molnar <mingo@kernel.org>,
Frederic Weisbecker <fweisbec@gmail.com>,
Peter Zijlstra <peterz@infradead.org>,
Andi Kleen <ak@linux.jf.intel.com>
Subject: Re: [PATCH RFC v2 0/4] perf: IRQ-bound performance events
Date: Sun, 5 Jan 2014 09:59:49 -0800 [thread overview]
Message-ID: <20140105175949.GC27909@tassilo.jf.intel.com> (raw)
In-Reply-To: <cover.1388858996.git.agordeev@redhat.com>
On Sat, Jan 04, 2014 at 07:22:32PM +0100, Alexander Gordeev wrote:
> Hello,
>
> This is version 2 of RFC "perf: IRQ-bound performance events". That is an
> introduction of IRQ-bound performance events - ones that only count in a
> context of a hardware interrupt handler. Ingo suggested to extend this
> functionality to softirq and threaded handlers as well:
Did you measure the overhead in workloads that do a lot of interrupts?
I assume two WRMSR could be a significant part of the cost of small interrupts.
For counting at least it would be likely a lot cheaper to just RDPMC
and subtract manually.
The cache miss example below is certainly misleading, as cache misses
by interrupts are often a "debt", that is they are forced on whoever
is interrupted. I don't think that is a good use of this.
I guess it can be useful for cycles.
-Andi
next prev parent reply other threads:[~2014-01-05 17:59 UTC|newest]
Thread overview: 10+ messages / expand[flat|nested] mbox.gz Atom feed top
2014-01-04 18:22 [PATCH RFC v2 0/4] perf: IRQ-bound performance events Alexander Gordeev
2014-01-04 18:22 ` [PATCH RFC v2 1/4] perf/core: " Alexander Gordeev
2014-01-04 18:22 ` [PATCH RFC v2 2/4] perf/x86: " Alexander Gordeev
2014-01-04 18:22 ` [PATCH RFC v2 3/4] perf/x86/Intel: " Alexander Gordeev
2014-01-04 18:22 ` [PATCH RFC v2 4/4] perf/tool: " Alexander Gordeev
2014-01-05 17:59 ` Andi Kleen [this message]
2014-01-13 13:23 ` [PATCH RFC v2 0/4] perf: " Alexander Gordeev
2014-01-13 15:50 ` Frederic Weisbecker
2014-01-14 16:07 ` Alexander Gordeev
2014-01-14 17:09 ` Frederic Weisbecker
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