From: Andi Kleen <ak@linux.intel.com>
To: Jiri Olsa <jolsa@redhat.com>
Cc: linux-kernel@vger.kernel.org,
Arnaldo Carvalho de Melo <acme@redhat.com>,
Corey Ashford <cjashfor@linux.vnet.ibm.com>,
Frederic Weisbecker <fweisbec@gmail.com>,
Ingo Molnar <mingo@elte.hu>, Paul Mackerras <paulus@samba.org>,
Peter Zijlstra <a.p.zijlstra@chello.nl>,
Don Zickus <dzickus@redhat.com>,
Andi Kleen <ak@linux.jf.intel.com>,
Adrian Hunter <adrian.hunter@intel.com>,
Stephane Eranian <eranian@google.com>
Subject: Re: [RFC 00/21] perf tools: Add toggling events support
Date: Wed, 25 Sep 2013 12:12:16 -0700 [thread overview]
Message-ID: <20130925191216.GE2018@tassilo.jf.intel.com> (raw)
In-Reply-To: <1380113447-17144-1-git-send-email-jolsa@redhat.com>
On Wed, Sep 25, 2013 at 02:50:26PM +0200, Jiri Olsa wrote:
> hi,
> sending *RFC* for toggling events support.
>
> Adding perf interface that allows to create toggle events, which can
> enable or disable another event. Whenever the toggle event is triggered
> (has overflow), it toggles another event state and either starts or
> stops it.
>
> The goal is to be able to create toggling tracepoint events to enable and
> disable HW counters, but the interface is generic enough to be used for
> any kind of event.
Haven't read the patches, but frequent full event switch in/out seems
very expensive. If someone puts that switch on a common
function it would likely disturb things quite a bit.
It would be better to keep counting and just do RDPMC on
the switch points, and then subtract for counting.
For sampling could need a MSR write to enable/disable.
Still somewhat expensive, but nowhere near as bad as a full switch.
Another problem is that it may be very inexact, as
the counting will often happen in the background
and not be very synchronized with the switches.
Not fully sure how big a problem that would be.
-Andi
next prev parent reply other threads:[~2013-09-25 19:12 UTC|newest]
Thread overview: 35+ messages / expand[flat|nested] mbox.gz Atom feed top
2013-09-25 12:50 [RFC 00/21] perf tools: Add toggling events support Jiri Olsa
2013-09-25 12:50 ` [PATCH 01/21] perf tools: Introduce perf_evlist__wait_workload function Jiri Olsa
2013-09-25 12:50 ` [PATCH 02/21] perf tools: Separate sys_perf_event_open call into evsel_open Jiri Olsa
2013-09-25 12:50 ` [PATCH 03/21] perf x86: Update event count properly for read syscall Jiri Olsa
2013-09-25 12:50 ` [PATCH 04/21] perf: Move event state initialization before/behind the pmu add/del calls Jiri Olsa
2013-09-25 12:50 ` [PATCH 05/21] perf: Add event toggle sys_perf_event_open interface Jiri Olsa
2013-09-25 22:36 ` Sukadev Bhattiprolu
2013-09-26 12:27 ` Jiri Olsa
2013-09-25 12:50 ` [PATCH 06/21] perf: Add event toggle ioctl interface Jiri Olsa
2013-09-25 19:46 ` Vince Weaver
2013-09-26 12:30 ` Jiri Olsa
2013-09-26 13:03 ` Vince Weaver
2013-09-25 12:50 ` [PATCH 07/21] perf: Toggle whole group in toggle event overflow Jiri Olsa
2013-09-25 12:50 ` [PATCH 08/21] perf: Add new 'paused' attribute Jiri Olsa
2013-09-25 22:41 ` Sukadev Bhattiprolu
2013-09-26 12:24 ` Jiri Olsa
2013-09-25 12:50 ` [PATCH 09/21] perf: Account toggle masters for toggled event Jiri Olsa
2013-09-25 12:50 ` [PATCH 10/21] perf: Be more specific on pmu related event init naming Jiri Olsa
2013-09-25 12:50 ` [PATCH 11/21] perf: Split allocation and initialization code Jiri Olsa
2013-09-25 12:50 ` [PATCH 12/21] perf: Support event inheritance for toggle feature Jiri Olsa
2013-09-25 12:50 ` [PATCH 13/21] perf tests: Adding event simple toggling test Jiri Olsa
2013-09-25 12:50 ` [PATCH 14/21] perf tests: Adding event group " Jiri Olsa
2013-09-25 12:50 ` [PATCH 15/21] perf tests: Adding event inherit " Jiri Olsa
2013-09-25 12:50 ` [PATCH 16/21] perf tools: Allow numeric event to change name via name term Jiri Olsa
2013-09-25 12:50 ` [PATCH 17/21] perf tools: Add event_config_optional parsing rule Jiri Olsa
2013-09-25 12:50 ` [PATCH 18/21] perf tools: Rename term related parsing function/variable properly Jiri Olsa
2013-09-25 12:50 ` [PATCH 19/21] perf tools: Carry term string value for symbols events Jiri Olsa
2013-09-25 12:50 ` [PATCH 20/21] perf tools: Add support to parse event on/off toggle terms Jiri Olsa
2013-09-25 12:50 ` [PATCH 21/21] perf tools: Add record/stat support for toggling events Jiri Olsa
2013-09-25 19:12 ` Andi Kleen [this message]
2013-09-26 7:03 ` [RFC 00/21] perf tools: Add toggling events support Ingo Molnar
2013-09-26 15:45 ` Andi Kleen
2013-09-26 12:11 ` Jiri Olsa
2013-09-26 11:31 ` Stephane Eranian
2013-09-26 12:20 ` Jiri Olsa
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