From: Josh Poimboeuf <jpoimboe@kernel.org>
To: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Cc: Peter Zijlstra <peterz@infradead.org>,
x86@kernel.org, Steven Rostedt <rostedt@goodmis.org>,
Ingo Molnar <mingo@kernel.org>,
Arnaldo Carvalho de Melo <acme@kernel.org>,
linux-kernel@vger.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>, Namhyung Kim <namhyung@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, Jordan Rome <jordalgo@meta.com>,
Sam James <sam@gentoo.org>,
linux-trace-kernel@vger.kernel.org,
Andrii Nakryiko <andrii.nakryiko@gmail.com>,
Jens Remus <jremus@linux.ibm.com>,
Florian Weimer <fweimer@redhat.com>,
Andy Lutomirski <luto@kernel.org>
Subject: Re: [PATCH v3 11/19] unwind: Add deferred user space unwinding API
Date: Wed, 30 Oct 2024 10:55:52 -0700 [thread overview]
Message-ID: <20241030175552.22cza6t7dfe3xy3p@treble.attlocal.net> (raw)
In-Reply-To: <20241030174752.gwzk6q6n2f3sg52a@treble.attlocal.net>
On Wed, Oct 30, 2024 at 10:47:55AM -0700, Josh Poimboeuf wrote:
> > Moving from per-cpu to per-task makes this cookie task-specific and not
> > global anymore, I don't think we want this for a stack walking
> > infrastructure meant to be used by various tracers. Also a global cookie
> > is more robust and does not depend on guaranteeing that all the
> > trace data is present to guarantee current thread ID accuracy and
> > thus that cookies match between deferred unwind request and their
> > fulfillment.
>
> I don't disagree. What I meant was, on entry (or exit), increment the
> task cookie *with* the CPU bits included.
>
> Or as you suggested previously, the "cookie" just be a struct with two
> fields: CPU # and per-task entry counter.
Never mind, that wouldn't work... Two tasks could have identical
per-task counters while being scheduled on the same CPU.
--
Josh
next prev parent reply other threads:[~2024-10-30 17:55 UTC|newest]
Thread overview: 7+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <cover.1730150953.git.jpoimboe@kernel.org>
[not found] ` <a94eb70a80c4a13dedb2655b7848304a992cb1b0.1730150953.git.jpoimboe@kernel.org>
[not found] ` <20241029135617.GB14555@noisy.programming.kicks-ass.net>
[not found] ` <20241029171752.4y67p3ob24riogpi@treble.attlocal.net>
[not found] ` <bcd11a07-45fb-442b-a25b-5cadc6aac0e6@efficios.com>
[not found] ` <20241029183440.fbwoistveyxneezt@treble.attlocal.net>
2024-10-30 13:44 ` [PATCH v3 11/19] unwind: Add deferred user space unwinding API Mathieu Desnoyers
2024-10-30 17:47 ` Josh Poimboeuf
2024-10-30 17:55 ` Josh Poimboeuf [this message]
2024-10-30 18:25 ` Josh Poimboeuf
[not found] ` <42c0a99236af65c09c8182e260af7bcf5aa1e158.1730150953.git.jpoimboe@kernel.org>
[not found] ` <20241105124053.523e93dd@gandalf.local.home>
2024-11-05 17:45 ` [PATCH v3 09/19] unwind: Introduce sframe user space unwinding Steven Rostedt
[not found] ` <1f83be89-b816-48a3-a7ee-9b72f07b558e@linux.ibm.com>
[not found] ` <20241113155040.6a9a1bed@gandalf.local.home>
[not found] ` <20241113211535.ghnw52wkgudkjvgv@jpoimboe>
[not found] ` <20241113171326.6d1ddc83@gandalf.local.home>
2024-11-13 22:21 ` Steven Rostedt
2024-11-13 22:25 ` Steven Rostedt
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