This is the mail archive of the
systemtap@sourceware.org
mailing list for the systemtap project.
Re: [PATCH -tip 1/3] [CLEANUP] perf-probe: Expand given path to absolute path
- From: Masami Hiramatsu <masami dot hiramatsu dot pt at hitachi dot com>
- To: Arnaldo Carvalho de Melo <acme at ghostprotocols dot net>
- Cc: Ingo Molnar <mingo at kernel dot org>, Srikar Dronamraju <srikar at linux dot vnet dot ibm dot com>, David Ahern <dsahern at gmail dot com>, lkml <linux-kernel at vger dot kernel dot org>, "Steven Rostedt (Red Hat)" <rostedt at goodmis dot org>, Oleg Nesterov <oleg at redhat dot com>, "David A. Long" <dave dot long at linaro dot org>, systemtap at sourceware dot org, yrl dot pp-manager dot tt at hitachi dot com, Namhyung Kim <namhyung at kernel dot org>
- Date: Tue, 24 Dec 2013 15:51:26 +0900
- Subject: Re: [PATCH -tip 1/3] [CLEANUP] perf-probe: Expand given path to absolute path
- Authentication-results: sourceware.org; auth=none
- References: <20131220100255 dot 7169 dot 19384 dot stgit at kbuild-fedora dot novalocal> <20131220100257 dot 7169 dot 60537 dot stgit at kbuild-fedora dot novalocal> <20131220180031 dot GA28878 at ghostprotocols dot net> <52B75B0D dot 6010401 at hitachi dot com> <20131223142832 dot GF28878 at ghostprotocols dot net>
(2013/12/23 23:28), Arnaldo Carvalho de Melo wrote:
> Em Mon, Dec 23, 2013 at 06:35:09AM +0900, Masami Hiramatsu escreveu:
>> (2013/12/21 3:00), Arnaldo Carvalho de Melo wrote:
>>> Em Fri, Dec 20, 2013 at 10:02:57AM +0000, Masami Hiramatsu escreveu:
>>>> Expand given path to absolute path in option parser,
>>>> except for a module name. Instead of expanding it later,
>>>> this get the absolute path in early stage.
>>>
>>> What is the problem this solves?
>>>
>>> Can you provide some output showing the problem, i.e. before you apply
>>> this patch?
>>
>> No, this is just a code cleanup, for the later enhancements.
>
> Ok, this is just a cleanup, but what does this cleanup achieves? Why is
> it better to "getting the absolute path in early stage"?
>
> I.e. you're describing what the patch does, and I can see it from
> reading code, but why is it good to do it in an early stage?
---
Since realpath at the later stage in processing several probe point
can be called several times(even if currently doesn't, it can happen
when we expands the feature), it is waste of the performance.
Processing it once at the early stage can avoid that.
---
Is that good enough for you? :)
>
>> Should I put it into the next patch?
>
> No need for that, just, please, clarify why it is needed.
>
OK, I'll do that:)
Thank you,
--
Masami HIRAMATSU
IT Management Research Dept. Linux Technology Center
Hitachi, Ltd., Yokohama Research Laboratory
E-mail: masami.hiramatsu.pt@hitachi.com