From: Andi Kleen <andi@firstfloor.org>
To: linux-kernel@vger.kernel.org, linux-perf-users@vger.kernel.org
Subject: Announcing simple-pt -- a simple Processor Trace implementation for Linux
Date: Mon, 17 Aug 2015 06:31:30 +0200 [thread overview]
Message-ID: <20150817043130.GI1747@two.firstfloor.org> (raw)
Modern Intel Core CPUs (5th and 6th generation) have a Intel Processor Trace (PT) feature
to trace branch execution with low overhead. This is useful for performance analysis and debugging.
simple-pt is a simple standalone driver and decoder tool to implement PT on Linux.
Starting with Linux 4.1 Linux has an integrated PT implementation in perf
(see https://lwn.net/Articles/648154/).
simple-pt is an alternative implementation. It has many disadvantages over the perf PT
implementation, such as:
- needs to run as root
- no long term tracing or sampling with interrupts
- no support for interactive debugging (use gdb 7.10 on perf for that)
- no support for histograms
- somewhat experimental
- not as well supported as perf
On the positive side simple-pt is:
- simple
- standalone. No kernel changes needed. Could be ported to older kernels or other operating systems
- easy to modify and experiment with
- more ftrace like decoding tool
- support for kprobes based triggers
- modular “unix style” design with simple tools that do only one thing each
- BSD licensed
Example output:
% sptcmd -c tcall taskset -c 0 ./tcall
cpu 0 offset 1027688, 1003 KB, writing to ptout.0
...
Wrote sideband to ptout.sideband
% sptdecode --sideband ptout.sideband --pt ptout.0 | less
TIME DELTA INSNs OPERATION
frequency 32
0 [+0] [+ 1] _dl_aux_init+436
[+ 6] __libc_start_main+455 -> _dl_discover_osversion
...
[+ 13] __libc_start_main+446 -> main
[+ 9] main+22 -> f1
[+ 4] f1+9 -> f2
[+ 2] f1+19 -> f2
[+ 5] main+22 -> f1
[+ 4] f1+9 -> f2
[+ 2] f1+19 -> f2
[+ 5] main+22 -> f1
...
Available from https://github.com/andikleen/simple-pt
--
ak@linux.intel.com -- Speaking for myself only.
next reply other threads:[~2015-08-17 4:31 UTC|newest]
Thread overview: 3+ messages / expand[flat|nested] mbox.gz Atom feed top
2015-08-17 4:31 Andi Kleen [this message]
2015-08-17 13:09 ` Announcing simple-pt -- a simple Processor Trace implementation for Linux Frederic Weisbecker
2015-08-17 18:21 ` Andi Kleen
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=20150817043130.GI1747@two.firstfloor.org \
--to=andi@firstfloor.org \
--cc=linux-kernel@vger.kernel.org \
--cc=linux-perf-users@vger.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).