From: Arun Sharma <asharma@fb.com>
To: Frederic Weisbecker <fweisbec@gmail.com>
Cc: linux-kernel@vger.kernel.org, Ingo Molnar <mingo@elte.hu>,
Arnaldo Carvalho de Melo <acme@redhat.com>,
Mike Galbraith <efault@gmx.de>, Paul Mackerras <paulus@samba.org>,
Peter Zijlstra <peterz@infradead.org>,
Stephane Eranian <eranian@google.com>,
Namhyung Kim <namhyung.kim@lge.com>,
Tom Zanussi <tzanussi@gmail.com>,
linux-perf-users@vger.kernel.org
Subject: Re: [PATCH] perf, x86: Disable sanity check
Date: Thu, 19 Apr 2012 10:33:32 -0700 [thread overview]
Message-ID: <4F904C6C.7020407@fb.com> (raw)
In-Reply-To: <20120419052208.GA29875@somewhere.redhat.com>
On 4/18/12 10:22 PM, Frederic Weisbecker wrote:
> So rbp is part of the JIT stack but not rsp?
> Do you have a practical example of that? I must confess I don't know
> much about JIT stack.
Nothing specific to JITs here. Any time an app has two stacks S1 and S2
(with S1 at a lower address and S2 at a higher address) and %rsp at the
time of a perf event is pointing to S2, we don't get traces beyond S2.
| |
| |
| 0x1000000 | <-- %rbp
| |
| |
S2: 0x2000000 | | <-- %rsp
| |
| |
| |
| frame3 |
| |
| frame2 |
| |
S1: 0x1000000 | frame1 |
| |
| |
| |
| |
gdb is able to show:
(gdb) bt
<frame at 0x2000000>
frame1
frame2
frame3
frame4
..
just fine.
In our use case, there may be multiple transitions between S1 and S2.
For eg: frame4 could be on S2 (i.e 0x2xxxxxx range).
-Arun
next prev parent reply other threads:[~2012-04-19 17:34 UTC|newest]
Thread overview: 6+ messages / expand[flat|nested] mbox.gz Atom feed top
2012-04-18 23:24 [PATCH] perf, x86: Disable sanity check Arun Sharma
2012-04-19 5:22 ` Frederic Weisbecker
2012-04-19 17:33 ` Arun Sharma [this message]
2012-04-20 9:11 ` Peter Zijlstra
2012-04-20 16:16 ` Linus Torvalds
2012-04-20 18:18 ` Arun Sharma
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