From: tip-bot for David Ahern <dsahern@gmail.com>
To: linux-tip-commits@vger.kernel.org
Cc: acme@redhat.com, linux-kernel@vger.kernel.org, hpa@zytor.com,
mingo@kernel.org, peterz@infradead.org, gleb@redhat.com,
robert.richter@amd.com, dsahern@gmail.com, tglx@linutronix.de,
avi@redhat.com
Subject: [tip:perf/urgent] perf tool: Precise mode requires exclude_guest
Date: Fri, 19 Oct 2012 17:55:38 -0700 [thread overview]
Message-ID: <tip-1342798cc13e3b48d9b5738f0c8fa812ccea8101@git.kernel.org> (raw)
In-Reply-To: <1347569955-54626-2-git-send-email-dsahern@gmail.com>
Commit-ID: 1342798cc13e3b48d9b5738f0c8fa812ccea8101
Gitweb: http://git.kernel.org/tip/1342798cc13e3b48d9b5738f0c8fa812ccea8101
Author: David Ahern <dsahern@gmail.com>
AuthorDate: Thu, 13 Sep 2012 14:59:13 -0600
Committer: Arnaldo Carvalho de Melo <acme@redhat.com>
CommitDate: Tue, 16 Oct 2012 12:43:31 -0300
perf tool: Precise mode requires exclude_guest
Summary of events per Peter:
"Intel PEBS in VT-x context uses the DS address as a guest linear address,
even though its programmed by the host as a host linear address. This
either results in guest memory corruption and or the hardware faulting and
'crashing' the virtual machine. Therefore we have to disable PEBS on VT-x
enter and re-enable on VT-x exit, enforcing a strict exclude_guest.
AMB IBS does work but doesn't currently support exclude_* at all,
setting an exclude_* bit will make it fail."
This patch handles userspace perf command, setting the exclude_guest
attribute if precise mode is requested, but only if a user has not
specified a request for guest or host only profiling (G or H attribute).
Kernel side AMD currently ignores all exclude_* bits, so there is no impact
to existing IBS code paths. Robert Richter has a patch where IBS code will
return EINVAL if an exclude_* bit is set. When this goes in it means use
of :p on AMD with IBS will first fail with EINVAL (because exclude_guest
will be set). Then the existing fallback code within perf will unset
exclude_guest and try again. The second attempt will succeed if the CPU
supports IBS profiling.
Signed-off-by: David Ahern <dsahern@gmail.com>
Acked-by: Peter Zijlstra <peterz@infradead.org>
Acked-by: Robert Richter <robert.richter@amd.com>
Tested-by: Robert Richter <robert.richter@amd.com>
Reviewed-by: Robert Richter <robert.richter@amd.com>
Cc: Avi Kivity <avi@redhat.com>
Cc: Gleb Natapov <gleb@redhat.com>
Cc: Ingo Molnar <mingo@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Robert Richter <robert.richter@amd.com>
Link: http://lkml.kernel.org/r/1347569955-54626-2-git-send-email-dsahern@gmail.com
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
---
tools/perf/util/parse-events.c | 3 +++
1 files changed, 3 insertions(+), 0 deletions(-)
diff --git a/tools/perf/util/parse-events.c b/tools/perf/util/parse-events.c
index aed38e4..75c7b0f 100644
--- a/tools/perf/util/parse-events.c
+++ b/tools/perf/util/parse-events.c
@@ -690,6 +690,9 @@ static int get_event_modifier(struct event_modifier *mod, char *str,
eH = 0;
} else if (*str == 'p') {
precise++;
+ /* use of precise requires exclude_guest */
+ if (!exclude_GH)
+ eG = 1;
} else
break;
next prev parent reply other threads:[~2012-10-20 0:56 UTC|newest]
Thread overview: 19+ messages / expand[flat|nested] mbox.gz Atom feed top
2012-09-13 20:59 [PATCH 0/3 v3] perf: precise mode and exclude_guest David Ahern
2012-09-13 20:59 ` [PATCH 1/3] perf tool: precise mode requires exclude_guest David Ahern
2012-10-20 0:55 ` tip-bot for David Ahern [this message]
2012-09-13 20:59 ` [PATCH 2/3] perf: require exclude_guest to use PEBS - kernel side enforcement David Ahern
2012-10-20 0:56 ` [tip:perf/urgent] perf: Require " tip-bot for Peter Zijlstra
2012-09-13 20:59 ` [PATCH 3/3 v2] perf tool: give user better message if precise is not supported David Ahern
2012-09-14 5:43 ` Ingo Molnar
2012-09-14 11:13 ` David Ahern
2012-09-14 11:36 ` Ingo Molnar
2012-09-14 11:43 ` David Ahern
2012-09-14 18:00 ` Arnaldo Carvalho de Melo
2012-09-14 18:07 ` Peter Zijlstra
2012-09-14 20:05 ` Ingo Molnar
2012-09-14 20:11 ` Ingo Molnar
2012-09-14 21:26 ` Peter Zijlstra
2012-09-17 7:11 ` Ingo Molnar
2012-10-25 8:01 ` [tip:perf/core] perf tools: Give " tip-bot for David Ahern
2012-09-26 1:24 ` [PATCH 0/3 v3] perf: precise mode and exclude_guest David Ahern
2012-10-09 15:08 ` David Ahern
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