From: Andi Kleen <ak@linux.intel.com>
To: Arnaldo Carvalho de Melo <arnaldo.melo@gmail.com>
Cc: Adrian Hunter <adrian.hunter@intel.com>,
Jiri Olsa <jolsa@redhat.com>,
linux-kernel@vger.kernel.org, Namhyung Kim <namhyung@kernel.org>,
linux-perf-users@vger.kernel.org
Subject: Re: [PATCH 11/16] perf intel-pt: Add support for synthesizing callchains for regular events
Date: Sun, 19 Apr 2020 20:04:57 -0700 [thread overview]
Message-ID: <20200420030457.GA608746@tassilo.jf.intel.com> (raw)
In-Reply-To: <20200417213704.GB21512@kernel.org>
> Andi? My concern is that if this is the optimal solution for a good
> subset of the machines out there, then we need to make it easy to use,
> even transparent, if possible and safe to take that path.
I'm not sure it's that great in the general case. A PT call graph
would need a full PT recording from start to end.
The problem with full PT recording is that it doesn't really work for a
lot of workloads, because for anything doing enough computation the CPU
just generates too much data and you end up with a lot of gaps in the
trace when the perf record flushing cannot keep up.
Also even if it worked you might end up with far too much data that
will take a long time to process.
So I suspect it wouldn't work often enough to be generally useful.
For the leader sample case we just want to use some non PT method
to get the call graph.
-Andi
prev parent reply other threads:[~2020-04-20 3:04 UTC|newest]
Thread overview: 4+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <20200401101613.6201-1-adrian.hunter@intel.com>
[not found] ` <20200401101613.6201-12-adrian.hunter@intel.com>
2020-04-16 15:14 ` [PATCH 11/16] perf intel-pt: Add support for synthesizing callchains for regular events Arnaldo Carvalho de Melo
2020-04-17 13:50 ` Adrian Hunter
2020-04-17 21:37 ` Arnaldo Carvalho de Melo
2020-04-20 3:04 ` Andi Kleen [this message]
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=20200420030457.GA608746@tassilo.jf.intel.com \
--to=ak@linux.intel.com \
--cc=adrian.hunter@intel.com \
--cc=arnaldo.melo@gmail.com \
--cc=jolsa@redhat.com \
--cc=linux-kernel@vger.kernel.org \
--cc=linux-perf-users@vger.kernel.org \
--cc=namhyung@kernel.org \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).