[<prev] [next>] [thread-next>] [day] [month] [year] [list]
Message-ID: <20150817043130.GI1747@two.firstfloor.org>
Date: Mon, 17 Aug 2015 06:31:30 +0200
From: Andi Kleen <andi@...stfloor.org>
To: linux-kernel@...r.kernel.org, linux-perf-users@...r.kernel.org
Subject: Announcing simple-pt -- a simple Processor Trace implementation for
Linux
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@...ux.intel.com -- Speaking for myself only.
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at http://vger.kernel.org/majordomo-info.html
Please read the FAQ at http://www.tux.org/lkml/
Powered by blists - more mailing lists