From: Ingo Molnar <mingo@kernel.org>
To: Peter Zijlstra <peterz@infradead.org>
Cc: Jiri Slaby <jslaby@suse.cz>, Josh Poimboeuf <jpoimboe@redhat.com>,
Jiri Kosina <jikos@kernel.org>,
Linus Torvalds <torvalds@linux-foundation.org>,
Andrew Morton <akpm@linux-foundation.org>,
live-patching@vger.kernel.org,
Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
Thomas Gleixner <tglx@linutronix.de>,
Ingo Molnar <mingo@redhat.com>, "H. Peter Anvin" <hpa@zytor.com>,
the arch/x86 maintainers <x86@kernel.org>,
Andy Lutomirski <luto@kernel.org>
Subject: Re: [PATCH 7/7] DWARF: add the config option
Date: Tue, 23 May 2017 09:27:38 +0200 [thread overview]
Message-ID: <20170523072738.vi5sakodet2boddr@gmail.com> (raw)
In-Reply-To: <20170523070701.hxalap5q54nrn6z5@hirez.programming.kicks-ass.net>
* Peter Zijlstra <peterz@infradead.org> wrote:
> On Wed, May 10, 2017 at 10:32:06AM +0200, Jiri Slaby wrote:
> > > But it does hurt, in the sense that the complicated format of DWARF CFI
> > > means the unwinder has to jump through a lot more hoops to read it.
> >
> > Why that matters, actually? Unwinder is nothing to be performance
> > oriented. And if somebody is doing a lot of unwinding during runtime,
> > they can switch to in-this-case-faster FP unwinder.
>
> perf (and ftrace) like the unwinder to be considered performance
> oriented.
Yes, and given how critical debugging is there's a kind of useful synergy here:
overall the perf unwinder is run about 10 orders of magnitude more often than the
debugging unwinder, so it's a very big help in shaking out unwinder/debug-info
bugs and increasing robustness overall.
The 'price' for using the unwinder in perf is that it has to be fast.
Thanks,
Ingo
next prev parent reply other threads:[~2017-05-23 7:27 UTC|newest]
Thread overview: 70+ messages / expand[flat|nested] mbox.gz Atom feed top
2017-05-05 12:21 [PATCH 1/7] DWARF: add option to preserve unwind info Jiri Slaby
2017-05-05 12:21 ` [PATCH 2/7] DWARF: EH-frame based stack unwinding Jiri Slaby
2017-05-05 12:21 ` [PATCH 3/7] vmlinux.lds: preserve eh_frame for DWARF unwinder Jiri Slaby
2017-05-05 12:21 ` [PATCH 4/7] DWARF: initialize structures for kernel and modules Jiri Slaby
2017-05-05 12:21 ` [PATCH 5/7] unwinder: show_stack, check also ret_addr_p's contents Jiri Slaby
2017-05-05 12:21 ` [PATCH 6/7] unwinder: plug in the DWARF unwinder Jiri Slaby
2017-05-05 12:22 ` [PATCH 7/7] DWARF: add the config option Jiri Slaby
2017-05-05 19:57 ` Linus Torvalds
2017-05-06 7:19 ` Ingo Molnar
2017-05-10 7:46 ` Jiri Slaby
2017-05-06 14:24 ` Jiri Kosina
2017-05-07 16:55 ` Josh Poimboeuf
2017-05-07 17:59 ` Ingo Molnar
2017-05-07 18:08 ` hpa
2017-05-07 21:48 ` Josh Poimboeuf
2017-05-08 7:50 ` Vojtech Pavlik
2017-05-08 13:14 ` Josh Poimboeuf
2017-05-08 5:35 ` Andy Lutomirski
2017-05-08 6:15 ` Ingo Molnar
2017-05-08 14:40 ` Josh Poimboeuf
2017-05-08 18:57 ` hpa
2017-05-09 0:21 ` Andy Lutomirski
2017-05-09 1:38 ` Josh Poimboeuf
2017-05-09 2:31 ` Andy Lutomirski
2017-05-09 3:38 ` Josh Poimboeuf
2017-05-09 10:00 ` hpa
2017-05-09 14:58 ` Josh Poimboeuf
2017-05-09 16:46 ` H.J. Lu
2017-05-10 8:15 ` Jiri Slaby
2017-05-10 13:09 ` Josh Poimboeuf
2017-05-10 16:23 ` H.J. Lu
2017-05-09 18:47 ` Jiri Kosina
2017-05-09 19:22 ` Josh Poimboeuf
2017-05-10 8:32 ` Jiri Slaby
2017-05-10 13:13 ` Josh Poimboeuf
2017-05-23 7:07 ` Peter Zijlstra
2017-05-23 7:27 ` Ingo Molnar [this message]
2017-05-19 20:53 ` Josh Poimboeuf
2017-05-19 20:57 ` H. Peter Anvin
2017-05-19 20:59 ` H. Peter Anvin
2017-05-19 21:29 ` Josh Poimboeuf
2017-05-19 21:35 ` Josh Poimboeuf
2017-05-20 5:23 ` Andy Lutomirski
2017-05-20 16:20 ` Josh Poimboeuf
2017-05-20 17:19 ` Josh Poimboeuf
2017-05-20 20:01 ` H.J. Lu
2017-05-20 21:58 ` Andy Lutomirski
2017-05-20 22:20 ` H.J. Lu
2017-05-22 11:34 ` Jiri Kosina
2017-05-22 14:39 ` H.J. Lu
2017-05-22 21:07 ` H. Peter Anvin
2017-05-22 21:37 ` H. Peter Anvin
2017-05-22 22:11 ` Josh Poimboeuf
2017-05-20 20:16 ` Linus Torvalds
2017-05-20 21:56 ` Andy Lutomirski
2017-05-20 23:00 ` Linus Torvalds
2017-05-20 23:29 ` Linus Torvalds
2017-05-26 6:54 ` Jiri Slaby
2017-05-26 11:29 ` Jiri Slaby
2017-05-26 12:14 ` Josh Poimboeuf
2017-05-22 11:12 ` Ingo Molnar
2017-05-22 21:16 ` H. Peter Anvin
2017-05-22 23:23 ` Jiri Kosina
2017-05-23 5:49 ` Ingo Molnar
2017-05-26 19:16 ` hpa
2017-05-28 9:12 ` Ingo Molnar
2017-05-10 7:39 ` Jiri Slaby
2017-05-10 12:42 ` Josh Poimboeuf
2017-05-10 12:47 ` Jiri Slaby
2017-05-10 18:11 ` Linus Torvalds
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