From: Steven Rostedt <rostedt@goodmis.org>
To: Andi Kleen <andi@firstfloor.org>
Cc: x86@kernel.org, peterz@infradead.org,
linux-kernel@vger.kernel.org, Andi Kleen <ak@linux.intel.com>
Subject: Re: [PATCH 3/4] x86: Add trace point for MSR accesses
Date: Tue, 1 Dec 2015 21:03:34 -0500 [thread overview]
Message-ID: <20151201210334.4a1f9ea1@grimm.local.home> (raw)
In-Reply-To: <1449018060-1742-3-git-send-email-andi@firstfloor.org>
On Tue, 1 Dec 2015 17:00:59 -0800
Andi Kleen <andi@firstfloor.org> wrote:
> From: Andi Kleen <ak@linux.intel.com>
>
> For debugging low level code interacting with the CPU
> it is often useful to trace the MSR read/writes. This gives
> a concise summary of PMU and other operations.
>
> perf has an ad-hoc way to do this using trace_printk,
> but it's somewhat limited (and also now spews ugly boot
> messages when enabled)
>
> Instead define real trace points for all MSR accesses.
>
> This adds three new trace points: read_msr and write_msr
> and rdpmc.
>
> They also report if the access faulted (if *_safe is used)
>
> This allows filtering and triggering on specific
> MSR values, which allows various more advanced
> debugging techniques.
>
> All the values are well defined in the CPU documentation.
>
> The trace can be post processed with
> Documentation/trace/postprocess/decode_msr.py
> to add symbolic MSR names to the trace.
>
> I only added it to native MSR accesses in C, not paravirtualized
> or in entry*.S (which is not too interesting)
>
> Originally the patch kit moved the MSRs out of line.
> This uses an alternative approach recommended by Steven Rostedt
> of only moving the trace calls out of line, but open coding the
> access to the jump label.
>
> v2:
> Move MSR trace events to arch/x86/include/asm/msr-trace.h
> Signed-off-by: Andi Kleen <ak@linux.intel.com>
>
For the general tracing part.
Acked-by: Steven Rostedt <rostedt@goodmis.org>
-- Steve
next prev parent reply other threads:[~2015-12-02 2:03 UTC|newest]
Thread overview: 25+ messages / expand[flat|nested] mbox.gz Atom feed top
2015-12-02 1:00 [PATCH 1/4] x86: Don't include asm/processor.h into asm/atomic.h Andi Kleen
2015-12-02 1:00 ` [PATCH 2/4] tracepoints: Move struct tracepoint to new tracepoint-defs.h header Andi Kleen
2015-12-02 1:56 ` Steven Rostedt
2015-12-04 11:59 ` [tip:perf/core] " tip-bot for Andi Kleen
2015-12-06 13:18 ` tip-bot for Andi Kleen
2015-12-02 1:00 ` [PATCH 3/4] x86: Add trace point for MSR accesses Andi Kleen
2015-12-02 2:03 ` Steven Rostedt [this message]
2015-12-04 11:59 ` [tip:perf/core] x86, tracing, perf: " tip-bot for Andi Kleen
2015-12-04 12:11 ` Borislav Petkov
2015-12-04 18:28 ` Andi Kleen
2015-12-04 18:30 ` Borislav Petkov
2015-12-04 22:18 ` Andi Kleen
2015-12-04 22:27 ` Borislav Petkov
2015-12-04 22:35 ` H. Peter Anvin
2015-12-04 22:48 ` Borislav Petkov
2015-12-04 22:57 ` H. Peter Anvin
2015-12-06 13:19 ` tip-bot for Andi Kleen
2015-12-02 1:01 ` [PATCH 4/4] perf, x86: Remove old MSR perf tracing code Andi Kleen
2015-12-04 12:00 ` [tip:perf/core] perf/x86: " tip-bot for Andi Kleen
2015-12-06 13:19 ` tip-bot for Andi Kleen
2015-12-04 11:58 ` [tip:perf/core] x86/headers: Don't include asm/processor.h in asm /atomic.h tip-bot for Andi Kleen
2015-12-06 13:18 ` tip-bot for Andi Kleen
-- strict thread matches above, loose matches on Subject: below --
2015-10-21 20:14 Adding MSR trace points, new edition Andi Kleen
2015-10-21 20:14 ` [PATCH 3/4] x86: Add trace point for MSR accesses Andi Kleen
2015-10-20 18:40 Adding MSR trace points, new edition Andi Kleen
2015-10-20 18:40 ` [PATCH 3/4] x86: Add trace point for MSR accesses Andi Kleen
2015-10-20 19:39 ` Steven Rostedt
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=20151201210334.4a1f9ea1@grimm.local.home \
--to=rostedt@goodmis.org \
--cc=ak@linux.intel.com \
--cc=andi@firstfloor.org \
--cc=linux-kernel@vger.kernel.org \
--cc=peterz@infradead.org \
--cc=x86@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).