From: tip-bot for Robert Richter <robert.richter@amd.com>
To: linux-tip-commits@vger.kernel.org
Cc: linux-kernel@vger.kernel.org, hpa@zytor.com, mingo@kernel.org,
robert.richter@amd.com, a.p.zijlstra@chello.nl,
tglx@linutronix.de
Subject: [tip:perf/core] perf/x86-ibs: Extend hw period that triggers overflow
Date: Wed, 9 May 2012 07:36:32 -0700 [thread overview]
Message-ID: <tip-7caaf4d8241feecafb87919402b0a6dbb1b71d9e@git.kernel.org> (raw)
In-Reply-To: <1333390758-10893-10-git-send-email-robert.richter@amd.com>
Commit-ID: 7caaf4d8241feecafb87919402b0a6dbb1b71d9e
Gitweb: http://git.kernel.org/tip/7caaf4d8241feecafb87919402b0a6dbb1b71d9e
Author: Robert Richter <robert.richter@amd.com>
AuthorDate: Mon, 2 Apr 2012 20:19:15 +0200
Committer: Ingo Molnar <mingo@kernel.org>
CommitDate: Wed, 9 May 2012 15:23:15 +0200
perf/x86-ibs: Extend hw period that triggers overflow
If the last hw period is too short we might hit the irq handler which
biases the results. Thus try to have a max last period that triggers
the sw overflow.
Signed-off-by: Robert Richter <robert.richter@amd.com>
Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Link: http://lkml.kernel.org/r/1333390758-10893-10-git-send-email-robert.richter@amd.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
---
arch/x86/kernel/cpu/perf_event_amd_ibs.c | 15 +++++++++++++--
1 files changed, 13 insertions(+), 2 deletions(-)
diff --git a/arch/x86/kernel/cpu/perf_event_amd_ibs.c b/arch/x86/kernel/cpu/perf_event_amd_ibs.c
index 3e32908..cb51a3e 100644
--- a/arch/x86/kernel/cpu/perf_event_amd_ibs.c
+++ b/arch/x86/kernel/cpu/perf_event_amd_ibs.c
@@ -85,8 +85,19 @@ perf_event_set_period(struct hw_perf_event *hwc, u64 min, u64 max, u64 *hw_perio
overflow = 1;
}
- if (left > max)
- left = max;
+ /*
+ * If the hw period that triggers the sw overflow is too short
+ * we might hit the irq handler. This biases the results.
+ * Thus we shorten the next-to-last period and set the last
+ * period to the max period.
+ */
+ if (left > max) {
+ left -= max;
+ if (left > max)
+ left = max;
+ else if (left < min)
+ left = min;
+ }
*hw_period = (u64)left;
next prev parent reply other threads:[~2012-05-09 14:36 UTC|newest]
Thread overview: 48+ messages / expand[flat|nested] mbox.gz Atom feed top
2012-04-02 18:19 [PATCH 00/12] perf/x86-ibs: Precise event sampling with IBS for AMD CPUs Robert Richter
2012-04-02 18:19 ` [PATCH 01/12] perf/x86-ibs: Fix update of period Robert Richter
2012-05-09 14:29 ` [tip:perf/core] " tip-bot for Robert Richter
2012-04-02 18:19 ` [PATCH 02/12] perf: Pass last sampling period to perf_sample_data_init() Robert Richter
2012-05-09 14:30 ` [tip:perf/core] " tip-bot for Robert Richter
2012-04-02 18:19 ` [PATCH 03/12] perf/x86-ibs: Enable ibs op micro-ops counting mode Robert Richter
2012-05-09 14:31 ` [tip:perf/core] " tip-bot for Robert Richter
2012-04-02 18:19 ` [PATCH 04/12] perf/x86-ibs: Fix frequency profiling Robert Richter
2012-05-09 14:32 ` [tip:perf/core] " tip-bot for Robert Richter
2012-04-02 18:19 ` [PATCH 05/12] perf/x86-ibs: Take instruction pointer from ibs sample Robert Richter
2012-05-09 14:33 ` [tip:perf/core] " tip-bot for Robert Richter
2012-04-02 18:19 ` [PATCH 06/12] perf/x86-ibs: Precise event sampling with IBS for AMD CPUs Robert Richter
2012-04-14 10:21 ` Peter Zijlstra
2012-04-23 9:56 ` Robert Richter
2012-04-27 12:34 ` Robert Richter
2012-04-27 12:39 ` Stephane Eranian
2012-04-27 12:54 ` Robert Richter
2012-04-27 13:10 ` Stephane Eranian
2012-04-27 15:18 ` Robert Richter
2012-04-27 15:30 ` Peter Zijlstra
2012-04-27 15:57 ` Stephane Eranian
2012-04-27 15:30 ` Peter Zijlstra
2012-04-27 16:09 ` Robert Richter
2012-04-27 16:21 ` Peter Zijlstra
2012-04-27 16:23 ` Stephane Eranian
2012-04-14 10:22 ` Peter Zijlstra
2012-04-23 8:41 ` Robert Richter
2012-04-23 10:36 ` Peter Zijlstra
2012-04-14 10:24 ` Peter Zijlstra
2012-04-23 10:08 ` Robert Richter
2012-05-02 10:33 ` [PATCH v2] " Robert Richter
2012-05-02 11:14 ` Peter Zijlstra
2012-05-04 17:53 ` Peter Zijlstra
2012-05-09 14:34 ` [tip:perf/core] " tip-bot for Robert Richter
2012-04-02 18:19 ` [PATCH 07/12] perf/x86-ibs: Rename some variables Robert Richter
2012-05-09 14:34 ` [tip:perf/core] " tip-bot for Robert Richter
2012-04-02 18:19 ` [PATCH 08/12] perf/x86-ibs: Trigger overflow if remaining period is too small Robert Richter
2012-05-09 14:35 ` [tip:perf/core] " tip-bot for Robert Richter
2012-04-02 18:19 ` [PATCH 09/12] perf/x86-ibs: Extend hw period that triggers overflow Robert Richter
2012-05-09 14:36 ` tip-bot for Robert Richter [this message]
2012-04-02 18:19 ` [PATCH 10/12] perf/x86-ibs: Implement workaround for IBS erratum #420 Robert Richter
2012-05-09 14:37 ` [tip:perf/core] " tip-bot for Robert Richter
2012-04-02 18:19 ` [PATCH 11/12] perf/x86-ibs: Catch spurious interrupts after stopping ibs Robert Richter
2012-05-09 14:38 ` [tip:perf/core] perf/x86-ibs: Catch spurious interrupts after stopping IBS tip-bot for Robert Richter
2012-04-02 18:19 ` [PATCH 12/12] perf/x86-ibs: Fix usage of IBS op current count Robert Richter
2012-05-09 14:39 ` [tip:perf/core] " tip-bot for Robert Richter
2012-04-02 19:11 ` [PATCH 00/12] perf/x86-ibs: Precise event sampling with IBS for AMD CPUs Ingo Molnar
2012-04-03 10:48 ` Robert Richter
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