From: Namhyung Kim <namhyung@kernel.org>
To: Josh Poimboeuf <jpoimboe@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>,
Steven Rostedt <rostedt@goodmis.org>,
Ingo Molnar <mingo@kernel.org>,
Arnaldo Carvalho de Melo <acme@kernel.org>,
linux-kernel@vger.kernel.org, x86@kernel.org,
Indu Bhagat <indu.bhagat@oracle.com>,
Mark Rutland <mark.rutland@arm.com>,
Alexander Shishkin <alexander.shishkin@linux.intel.com>,
Jiri Olsa <jolsa@kernel.org>, Ian Rogers <irogers@google.com>,
Adrian Hunter <adrian.hunter@intel.com>,
linux-perf-users@vger.kernel.org, Mark Brown <broonie@kernel.org>,
linux-toolchains@vger.kernel.org
Subject: Re: [PATCH RFC 04/10] perf: Introduce deferred user callchains
Date: Wed, 15 Nov 2023 08:13:31 -0800 [thread overview]
Message-ID: <ZVTuK5VRQfY1JOEY@google.com> (raw)
In-Reply-To: <CAM9d7chgoiwc3ZfQ8SzO7gV0oQOKMK3bJAdxa63Pzgcqo4i7tQ@mail.gmail.com>
On Mon, Nov 13, 2023 at 08:56:39AM -0800, Namhyung Kim wrote:
> On Sat, Nov 11, 2023 at 10:49 AM Josh Poimboeuf <jpoimboe@kernel.org> wrote:
> >
> > On Fri, Nov 10, 2023 at 10:57:58PM -0800, Namhyung Kim wrote:
> > > Anyway I'm not sure it can support these additional samples for
> > > deferred callchains without breaking the existing perf tools.
> > > Anyway it doesn't know PERF_CONTEXT_USER_DEFERRED at least.
> > > I think this should be controlled by a new feature bit in the
> > > perf_event_attr.
> > >
> > > Then we might add a breaking change to have a special
> > > sample record for the deferred callchains and sample ID only.
> >
> > Sounds like a good idea. I'll need to study the code to figure out how
> > to do that on the perf tool side. Or would you care to write a patch?
>
> Sure, I'd be happy to write one.
I think we can start with something like the below.
The sample id (attr.sample_type) should have
IDENTIFIER | TID | TIME to enable defer_callchain
in order to match sample and callchain records.
Thanks,
Namhyung
---8<---
diff --git a/include/uapi/linux/perf_event.h b/include/uapi/linux/perf_event.h
index 39c6a250dd1b..a3765ff59798 100644
--- a/include/uapi/linux/perf_event.h
+++ b/include/uapi/linux/perf_event.h
@@ -456,7 +456,8 @@ struct perf_event_attr {
inherit_thread : 1, /* children only inherit if cloned with CLONE_THREAD */
remove_on_exec : 1, /* event is removed from task on exec */
sigtrap : 1, /* send synchronous SIGTRAP on event */
- __reserved_1 : 26;
+ defer_callchain: 1, /* generate DEFERRED_CALLCHAINS records for userspace */
+ __reserved_1 : 25;
union {
__u32 wakeup_events; /* wakeup every n events */
@@ -1207,6 +1208,20 @@ enum perf_event_type {
*/
PERF_RECORD_AUX_OUTPUT_HW_ID = 21,
+ /*
+ * Deferred user stack callchains (for SFrame). Previous samples would
+ * have kernel callchains only and they need to be stitched with this
+ * to make full callchains.
+ *
+ * struct {
+ * struct perf_event_header header;
+ * u64 nr;
+ * u64 ips[nr];
+ * struct sample_id sample_id;
+ * };
+ */
+ PERF_RECORD_DEFERRED_CALLCHAINS = 22,
+
PERF_RECORD_MAX, /* non-ABI */
};
next prev parent reply other threads:[~2023-11-15 16:13 UTC|newest]
Thread overview: 30+ messages / expand[flat|nested] mbox.gz Atom feed top
2023-11-09 0:41 [PATCH RFC 00/10] perf: user space sframe unwinding Josh Poimboeuf
2023-11-09 0:41 ` [PATCH RFC 01/10] perf: Remove get_perf_callchain() 'init_nr' argument Josh Poimboeuf
2023-11-11 6:09 ` Namhyung Kim
2023-11-09 0:41 ` [PATCH RFC 02/10] perf: Remove get_perf_callchain() 'crosstask' argument Josh Poimboeuf
2023-11-11 6:11 ` Namhyung Kim
2023-11-11 20:53 ` Jordan Rome
2023-11-09 0:41 ` [PATCH RFC 03/10] perf: Simplify get_perf_callchain() user logic Josh Poimboeuf
2023-11-11 6:11 ` Namhyung Kim
2023-11-09 0:41 ` [PATCH RFC 04/10] perf: Introduce deferred user callchains Josh Poimboeuf
2023-11-11 6:57 ` Namhyung Kim
2023-11-11 18:49 ` Josh Poimboeuf
2023-11-11 18:54 ` Josh Poimboeuf
2023-11-13 16:56 ` Namhyung Kim
2023-11-13 17:21 ` Peter Zijlstra
2023-11-13 17:48 ` Namhyung Kim
2023-11-13 18:49 ` Peter Zijlstra
2023-11-13 19:16 ` Namhyung Kim
2023-11-15 16:13 ` Namhyung Kim [this message]
2023-11-20 14:03 ` Peter Zijlstra
2023-11-09 0:41 ` [PATCH RFC 05/10] perf/x86: Add HAVE_PERF_CALLCHAIN_DEFERRED Josh Poimboeuf
2023-11-09 0:41 ` [PATCH RFC 06/10] unwind: Introduce generic user space unwinding interfaces Josh Poimboeuf
2023-11-09 0:41 ` [PATCH RFC 07/10] unwind/x86: Add HAVE_USER_UNWIND Josh Poimboeuf
2023-11-09 0:41 ` [PATCH RFC 08/10] perf/x86: Use user_unwind interface Josh Poimboeuf
2023-11-09 0:41 ` [PATCH RFC 09/10] unwind: Introduce SFrame user space unwinding Josh Poimboeuf
2023-11-09 19:31 ` Indu Bhagat
2023-11-09 19:37 ` Josh Poimboeuf
2023-11-09 19:49 ` Steven Rostedt
2023-11-09 19:53 ` Josh Poimboeuf
2023-11-09 0:41 ` [PATCH RFC 10/10] unwind/x86/64: Add HAVE_USER_UNWIND_SFRAME Josh Poimboeuf
2023-11-09 0:45 ` [PATCH RFC 00/10] perf: user space sframe unwinding Josh Poimboeuf
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