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From: Peter Zijlstra <peterz@infradead.org>
To: "Liang, Kan" <kan.liang@linux.intel.com>
Cc: acme@redhat.com, mingo@kernel.org, linux-kernel@vger.kernel.org,
	jolsa@kernel.org, eranian@google.com,
	alexander.shishkin@linux.intel.com, ak@linux.intel.com
Subject: Re: [PATCH V6 11/14] perf/x86/intel: Disable sample-read the slots and metrics events
Date: Tue, 21 Jul 2020 21:18:11 +0200	[thread overview]
Message-ID: <20200721191811.GH10769@hirez.programming.kicks-ass.net> (raw)
In-Reply-To: <b24b9bd3-bbfb-98d4-4df3-c263e002dcf5@linux.intel.com>

On Tue, Jul 21, 2020 at 12:07:29PM -0400, Liang, Kan wrote:

> I'm trying to produce the bug mentioned above, but I'm not sure under what
> situation, the core code will 'promote' the sibling metric events?

Create an event group:

	fd = sys_perf_event_open();
	fd1 = sys_perf_event_open(.group_fd = fd);
	...

then kill the group leader:

	close(fd);

Then the sibling events: fdN, should get promoted. Ideally try and use
fd1 in a read or so after this.

> I tried the suggested code below. It works well for the sample-read case.
> Perf tool errors out as expected.

I'm not sure you can create that case with perf-tool, it's a bit of a
daft thing to do, so you'll have to write a custom program.

  reply	other threads:[~2020-07-21 19:18 UTC|newest]

Thread overview: 34+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-07-17 14:05 [PATCH V6 00/14] TopDown metrics support for Icelake kan.liang
2020-07-17 14:05 ` [PATCH V6 01/14] perf/x86: Use event_base_rdpmc for the RDPMC userspace support kan.liang
2020-07-17 14:05 ` [PATCH V6 02/14] perf/x86/intel: Name the global status bit in NMI handler kan.liang
2020-07-17 14:05 ` [PATCH V6 03/14] perf/x86/intel: Introduce the fourth fixed counter kan.liang
2020-07-20 16:20   ` Peter Zijlstra
2020-07-20 18:22     ` Liang, Kan
2020-07-17 14:05 ` [PATCH V6 04/14] perf/x86/intel: Move BTS index to 47 kan.liang
2020-07-17 14:05 ` [PATCH V6 05/14] perf/x86/intel: Fix the name of perf METRICS kan.liang
2020-07-17 14:05 ` [PATCH V6 06/14] perf/x86/intel: Use switch in intel_pmu_disable/enable_event kan.liang
2020-07-20 16:22   ` Peter Zijlstra
2020-07-20 19:02     ` Liang, Kan
2020-07-17 14:05 ` [PATCH V6 07/14] perf/x86/intel: Generic support for hardware TopDown metrics kan.liang
2020-07-20 17:41   ` Peter Zijlstra
2020-07-20 18:11     ` Liang, Kan
2020-07-21  9:43   ` Peter Zijlstra
2020-07-21 14:05     ` Liang, Kan
2020-07-21 14:25       ` peterz
2020-07-17 14:05 ` [PATCH V6 08/14] perf/x86: Add a macro for RDPMC offset of fixed counters kan.liang
2020-07-17 14:05 ` [PATCH V6 09/14] perf/x86/intel: Support TopDown metrics on Ice Lake kan.liang
2020-07-21 12:40   ` Peter Zijlstra
2020-07-21 14:23     ` Liang, Kan
2020-07-21 14:31       ` peterz
2020-07-21 15:50         ` Liang, Kan
2020-07-21 17:38     ` Andi Kleen
2020-07-21 19:20       ` Peter Zijlstra
2020-07-17 14:05 ` [PATCH V6 10/14] perf/x86/intel: Support per-thread RDPMC TopDown metrics kan.liang
2020-07-17 14:05 ` [PATCH V6 11/14] perf/x86/intel: Disable sample-read the slots and metrics events kan.liang
2020-07-21 13:10   ` Peter Zijlstra
2020-07-21 16:07     ` Liang, Kan
2020-07-21 19:18       ` Peter Zijlstra [this message]
2020-07-22 19:26     ` Liang, Kan
2020-07-17 14:05 ` [PATCH V6 12/14] perf, tools, stat: Support new per thread TopDown metrics kan.liang
2020-07-17 14:05 ` [PATCH V6 13/14] perf, tools, stat: Check Topdown Metric group kan.liang
2020-07-17 14:05 ` [PATCH V6 14/14] perf, tools: Add documentation for topdown metrics kan.liang

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