From: Hemant <hkshaw@linux.vnet.ibm.com>
To: Masami Hiramatsu <masami.hiramatsu.pt@hitachi.com>
Cc: linux-kernel@vger.kernel.org, srikar@linux.vnet.ibm.com,
peterz@infradead.org, oleg@redhat.com,
hegdevasant@linux.vnet.ibm.com, mingo@redhat.com,
anton@redhat.com, systemtap@sourceware.org,
namhyung@kernel.org, aravinda@linux.vnet.ibm.com
Subject: Re: [PATCH v2 0/3] Perf support to SDT markers
Date: Tue, 08 Oct 2013 12:54:00 -0000 [thread overview]
Message-ID: <5254005F.4010103@linux.vnet.ibm.com> (raw)
In-Reply-To: <5253A04E.4020809@hitachi.com>
On 10/08/2013 11:33 AM, Masami Hiramatsu wrote:
> Hi,
Hi Masami and thanks a lot for testing these patches.
>
> (2013/10/07 15:46), Hemant Kumar wrote:
>> This patchset helps in probing dtrace style markers(SDT) present in user space
>> applications through perf. Notes/markes are placed at important places by the
>> developers. They have a negligible overhead when not enabled. We can enable
>> them and probe at these places and find some important information like the
>> arguments' values, etc.
> Thank you for updating!
> By the way, could you rebase this series to the latest -tip kernel next time?
> It is more convenient for us to test & merge it.
Yes, I will rebase this series next time.
>
> [...]
>> - Now use perf to list the markers in the app:
>> # perf probe --markers -x ./user_app
>>
>> %user_app:foo_start
>> %user_app:fun_start
> Here, what I got.
>
> $ ./perf probe --markers -x /lib64/librt.so
> %librt:lll_futex_wake
>
> OK, it lists up markers.
>
> $ ./perf probe --markers -x ./perf
> SDT markers not present!
> Error : Failed to find SDT markers!(-1)
>
> OK, this shows an error, INHO, it'd better show which binary doesn't have markers.
OK, will include the binary name too.
>
> $ ./perf probe --markers
> Failed to open (null)
> Error : Failed to find SDT markers!(-1)
>
> Hmm, it's a bit odd error. It should check if there is an elf binary is specified.
Yeah, correct.
>
> $ ./perf probe --markers /lib64/librt.so
> %librt:lll_futex_wake
>
> It seems to work without -x. However, that is only when the path is started with /.
> And also the usage is not described by --help.
>
> $ ./perf probe --markers ./perf
> Semantic error :File always requires line number or lazy pattern.
> Error: Parse Error. (-22)
>
> So, to avoid confusion, --markers should abort without -x(--exec) option.
Yes, we can restrict action of --markers for -x option only. I thought
of keeping the same behavior as in case of function listing but I guess
restricting it would be better since, --markers should only be available
in user space.
>
>> - And then use perf probe to add a probe point :
>>
>> # perf probe -x ./user_app -a '%user_app:foo_start'
> And also, without -x, -a also exits with an odd error message.
>
> $ ./perf probe -a %libm:slowexp_p6
> Failed to open (null)
> Error: Failed to add events. (-1)
Ok, will rectify this behavior.
>
> I'll review each patch soon.
Thanks, looking forward to that.
- Hemant
prev parent reply other threads:[~2013-10-08 12:54 UTC|newest]
Thread overview: 18+ messages / expand[flat|nested] mbox.gz Atom feed top
2013-10-07 6:47 Hemant Kumar
2013-10-07 6:48 ` [PATCH v2 1/3] SDT markers listing by perf: Hemant Kumar
2013-10-08 8:57 ` Namhyung Kim
2013-10-08 13:04 ` Hemant
2013-10-08 11:39 ` Masami Hiramatsu
2013-10-08 13:25 ` Hemant
2013-10-07 6:48 ` [PATCH v2 2/3] Support for perf to probe into SDT markers: Hemant Kumar
2013-10-08 9:09 ` Namhyung Kim
2013-10-08 13:09 ` Hemant
2013-10-08 11:47 ` Masami Hiramatsu
2013-10-08 13:30 ` Hemant
2013-10-07 6:48 ` [PATCH v2 3/3] Documentation regarding perf/sdt Hemant Kumar
2013-10-07 15:48 ` [PATCH v2 0/3] Perf support to SDT markers Frank Ch. Eigler
2013-10-08 9:10 ` Namhyung Kim
2013-10-08 13:10 ` Hemant
2013-10-08 13:32 ` Hemant
2013-10-08 6:04 ` Masami Hiramatsu
2013-10-08 12:54 ` Hemant [this message]
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