From: Tony Garnock-Jones <tonyg@leastfixedpoint.com>
To: "Alex Xu (Hello71)" <alex_y_xu@yahoo.ca>,
acme@kernel.org, mingo@redhat.com, peterz@infradead.org
Cc: linux-perf-users@vger.kernel.org
Subject: Re: [PATCH] tools/perf: Use long-running addr2line per dso
Date: Fri, 10 Sep 2021 10:54:28 +0200 [thread overview]
Message-ID: <a5ab52f2-c898-d0fa-c2ec-0ee734ee9c0a@leastfixedpoint.com> (raw)
In-Reply-To: <1631205749.uhek9ofd69.none@localhost>
Hi Alex,
Thanks for taking a look at the patch!
On 9/9/21 6:52 PM, Alex Xu (Hello71) wrote:
> This patch seems awfully complicated, especially considering it still
> uses relatively slow stdio instead of direct library calls.
It is comparable in speed to the libbfd variant, apparently: in
https://bugs.debian.org/cgi-bin/bugreport.cgi?bug=911815#38, Steinar
Gunderson reports that the bfd and patched non-bfd versions have similar
run-times.
The complication is a bit of a shame, but I think it's reasonable given
that it is essentially reimplementing a variant of popen(3) with
bidirectional communication.
> Did you look
> into calling elfutils instead of libbfd if the latter is not available?
No, I didn't; I don't know the domain very well, so I adapted the
existing solution to run more efficiently.
> On the patch specifically, why was popen changed to socketpair? It looks
> like it adds significant complexity, and the advanced features of
> socketpair are not being used (SOCK_DGRAM/SOCK_SEQPACKET, SCM_RIGHTS).
Because popen is unidirectional, and with a long-running process we need
bidirectional communication. I could have used two pipes, but I figured
socketpair was just sitting there and why spend the extra two fds if I
didn't have to?
Regards,
Tony
next prev parent reply other threads:[~2021-09-10 8:54 UTC|newest]
Thread overview: 17+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-09-09 11:22 [PATCH] tools/perf: Use long-running addr2line per dso Tony Garnock-Jones
2021-09-09 16:52 ` Alex Xu (Hello71)
2021-09-09 20:19 ` Arnaldo Carvalho de Melo
2021-09-10 8:58 ` Tony Garnock-Jones
2021-09-10 8:54 ` Tony Garnock-Jones [this message]
2021-09-09 19:05 ` Ian Rogers
2021-09-10 8:57 ` Tony Garnock-Jones
2021-09-10 10:23 ` [PATCH v2] " Tony Garnock-Jones
2021-09-10 22:45 ` Ian Rogers
2021-09-10 22:55 ` Tony Garnock-Jones
2021-09-10 22:55 ` [PATCH v3] " Tony Garnock-Jones
2021-09-11 0:25 ` Ian Rogers
2021-09-13 20:05 ` Arnaldo Carvalho de Melo
2021-09-16 12:09 ` [PATCH v4] " Tony Garnock-Jones
2021-10-01 0:29 ` Ian Rogers
2021-10-01 1:20 ` Arnaldo Carvalho de Melo
2021-10-04 12:29 ` Arnaldo Carvalho de Melo
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