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From: Tony Garnock-Jones <>
To: "Alex Xu (Hello71)" <>,,,
Subject: Re: [PATCH] tools/perf: Use long-running addr2line per dso
Date: Fri, 10 Sep 2021 10:54:28 +0200	[thread overview]
Message-ID: <> (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, Steinar 
Gunderson reports that the bfd and patched non-bfd versions have similar 

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?


  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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