From: "Wangnan (F)" <wangnan0@huawei.com>
To: Ingo Molnar <mingo@kernel.org>
Cc: Jiri Olsa <jolsa@kernel.org>,
Arnaldo Carvalho de Melo <acme@kernel.org>,
David Ahern <dsahern@gmail.com>,
Peter Zijlstra <peterz@infradead.org>,
Milian Wolff <milian.wolff@kdab.com>,
<linux-kernel@vger.kernel.org>, pi3orama <pi3orama@163.com>,
lizefan 00213767 <lizefan@huawei.com>
Subject: Re: [BUG REPORT] perf tools: x86_64: Broken calllchain when sampling taken at 'callq' instruction
Date: Thu, 19 Nov 2015 14:45:13 +0800 [thread overview]
Message-ID: <564D6FF9.3030105@huawei.com> (raw)
In-Reply-To: <20151119063709.GA14852@gmail.com>
On 2015/11/19 14:37, Ingo Molnar wrote:
> * Wangnan (F) <wangnan0@huawei.com> wrote:
>
>>> perf cmdline is
>>>
>>> # ./pref record -g -F 9 --call-graph dwarf ./test_dwarf_unwind
>>>
>>> Use default events, precise_ip == 2 so uses PEBS.
>>>
>> Testetd 'cycles', 'cycles:p' and 'cycles:pp'. Only 'cycles:pp' captures
>> sample at callq. So maybe a PEBS problem?
> Well, that's how our PEBS sampling works: we roll back the instruction pointer to
> point at the instruction generating the sample. The state itself is
> post-instruction.
Just for curiosity:
how the interrupted process continue to execute, when the PC
saved in pt_regs still pointed to 'callq' but SP and stack has
already changes? Do we fix it in kernel, or by hardware?
Thank you.
next prev parent reply other threads:[~2015-11-19 6:45 UTC|newest]
Thread overview: 20+ messages / expand[flat|nested] mbox.gz Atom feed top
2015-11-18 7:20 [BUG REPORT] perf tools: x86_64: Broken calllchain when sampling taken at 'callq' instruction Wangnan (F)
2015-11-18 8:00 ` Wangnan (F)
2015-11-18 8:20 ` Ingo Molnar
2015-11-18 8:42 ` Wangnan (F)
2015-11-18 8:49 ` Wangnan (F)
2015-11-19 6:37 ` Ingo Molnar
2015-11-19 6:45 ` Wangnan (F) [this message]
2015-11-19 10:23 ` Ingo Molnar
2015-11-19 10:43 ` Wangnan (F)
2015-11-19 11:28 ` Peter Zijlstra
2015-11-19 11:23 ` Peter Zijlstra
2015-11-27 8:38 ` Ingo Molnar
2015-11-30 9:28 ` Peter Zijlstra
2015-12-01 7:28 ` Ingo Molnar
2015-12-01 8:38 ` Peter Zijlstra
2015-12-01 16:11 ` Ingo Molnar
2015-12-01 17:21 ` Peter Zijlstra
2015-12-02 9:55 ` Ingo Molnar
2015-11-18 8:48 ` Jiri Olsa
2015-11-18 9:02 ` Wangnan (F)
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