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From: Peter Zijlstra <peterz@infradead.org>
To: Steven Rostedt <rostedt@goodmis.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>,
	Josh Poimboeuf <jpoimboe@redhat.com>,
	Thomas Gleixner <tglx@linutronix.de>, Peter Anvin <hpa@zytor.com>,
	Julien Thierry <julien.thierry@arm.com>,
	Will Deacon <will.deacon@arm.com>,
	Andy Lutomirski <luto@amacapital.net>,
	Ingo Molnar <mingo@kernel.org>,
	Catalin Marinas <catalin.marinas@arm.com>,
	James Morse <james.morse@arm.com>,
	valentin.schneider@arm.com, Brian Gerst <brgerst@gmail.com>,
	Andrew Lutomirski <luto@kernel.org>,
	Borislav Petkov <bp@alien8.de>,
	Denys Vlasenko <dvlasenk@redhat.com>,
	Linux List Kernel Mailing <linux-kernel@vger.kernel.org>,
	Dmitry Vyukov <dvyukov@google.com>,
	Slavomir Kaslev <kaslevs@vmware.com>
Subject: Re: [PATCH 00/20] objtool: UACCESS validation v3
Date: Sun, 10 Mar 2019 14:16:20 +0100	[thread overview]
Message-ID: <20190310131620.GL2482@worktop.programming.kicks-ass.net> (raw)
In-Reply-To: <20190307131841.3b5d9e00@oasis.local.home>

On Thu, Mar 07, 2019 at 01:18:41PM -0500, Steven Rostedt wrote:
> On Thu, 7 Mar 2019 09:45:35 -0800
> Linus Torvalds <torvalds@linux-foundation.org> wrote:
> 
> > On Thu, Mar 7, 2019 at 9:38 AM Peter Zijlstra <peterz@infradead.org> wrote:
> > >
> > > Also; it seems to me that something PT, or maybe even simply:
> > >
> > >   perf -e branches -e branch-misses
> > >
> > > would get you similar or sufficient information.  

> I currently have one of my engineers looking at the data and may be
> sending patches soon. It's basically an entry level way to get into
> kernel development. Note, no patch will be sent just because of the
> data from the profiling. The task is to look at and understand the
> code, and see if it can be optimized (with likely/unlikely or flow
> changes). It's a way to get a better understanding of the kernel in
> various locations. It is by no means "profiler said this, lets change
> it." All changes must be rational, and make sense. The profiler is only
> used to help find those places.

Can't you just have those same engineers look at perf data? This seems
like a very expensive and convoluted way of getting something.


  reply	other threads:[~2019-03-10 13:16 UTC|newest]

Thread overview: 100+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-03-07 11:45 [PATCH 00/20] objtool: UACCESS validation v3 Peter Zijlstra
2019-03-07 11:45 ` [PATCH 01/20] x86/ia32: Fix ia32_restore_sigcontext AC leak Peter Zijlstra
2019-03-07 11:45 ` [PATCH 02/20] i915,uaccess: Fix redundant CLAC Peter Zijlstra
2019-03-07 11:45 ` [PATCH 03/20] x86/uaccess: Move copy_user_handle_tail into asm Peter Zijlstra
2019-03-08 18:53   ` Josh Poimboeuf
2019-03-08 19:48     ` Peter Zijlstra
2019-03-08 19:53       ` Josh Poimboeuf
2019-03-10 13:22         ` Peter Zijlstra
2019-03-07 11:45 ` [PATCH 04/20] x86/uaccess: Fix up the fixup Peter Zijlstra
2019-03-07 11:45 ` [PATCH 05/20] x86/uaccess/xen: Suppress SMAP warnings Peter Zijlstra
2019-03-07 12:22   ` Juergen Gross
2019-03-07 12:32     ` Peter Zijlstra
2019-03-07 12:36       ` Juergen Gross
2019-03-08 19:00   ` Josh Poimboeuf
2019-03-08 19:03     ` Josh Poimboeuf
2019-03-10 13:19       ` Peter Zijlstra
2019-03-11 17:59         ` Josh Poimboeuf
2019-03-08 19:50     ` Peter Zijlstra
2019-03-07 11:45 ` [PATCH 06/20] x86/uaccess: Always inline user_access_begin() Peter Zijlstra
2019-03-07 11:45 ` [PATCH 07/20] x86/uaccess: Always inline force_valid_ss() Peter Zijlstra
2019-03-07 13:50   ` Peter Zijlstra
2019-03-07 18:05   ` Andy Lutomirski
2019-03-07 18:59     ` Peter Zijlstra
2019-03-07 19:06       ` Andy Lutomirski
2019-03-07 11:45 ` [PATCH 08/20] x86/uaccess: Introduce user_access_{save,restore}() Peter Zijlstra
2019-03-07 11:45 ` [PATCH 09/20] x86/uaccess,kasan: Fix KASAN vs SMAP Peter Zijlstra
2019-03-07 11:45 ` [PATCH 10/20] x86/uaccess,ubsan: Fix UBSAN " Peter Zijlstra
2019-03-07 11:45 ` [PATCH 11/20] x86/uaccess,ftrace: Fix ftrace_likely_update() " Peter Zijlstra
2019-03-07 11:45 ` [PATCH 12/20] objtool: Set insn->func for alternatives Peter Zijlstra
2019-03-08 19:16   ` Josh Poimboeuf
2019-03-08 19:51     ` Peter Zijlstra
2019-03-07 11:45 ` [PATCH 13/20] objtool: Hande function aliases Peter Zijlstra
2019-03-08 19:23   ` Josh Poimboeuf
2019-03-08 19:52     ` Peter Zijlstra
2019-03-08 20:00       ` Josh Poimboeuf
2019-03-07 11:45 ` [PATCH 14/20] objtool: Rewrite add_ignores() Peter Zijlstra
2019-03-08 19:29   ` Josh Poimboeuf
2019-03-07 11:45 ` [PATCH 15/20] objtool: Add --backtrace support Peter Zijlstra
2019-03-08 19:33   ` Josh Poimboeuf
2019-03-07 11:45 ` [PATCH 16/20] objtool: Rewrite alt->skip_orig Peter Zijlstra
2019-03-08 20:15   ` Josh Poimboeuf
2019-03-08 21:34     ` Peter Zijlstra
2019-03-08 22:27       ` Josh Poimboeuf
2019-03-07 11:45 ` [PATCH 17/20] objtool: Fix sibling call detection Peter Zijlstra
2019-03-08 20:22   ` Josh Poimboeuf
2019-03-07 11:45 ` [PATCH 18/20] objtool: Add UACCESS validation Peter Zijlstra
2019-03-07 16:33   ` Linus Torvalds
2019-03-07 17:10     ` hpa
2019-03-07 17:41     ` Peter Zijlstra
2019-03-07 17:54       ` Linus Torvalds
2019-03-07 18:48         ` Peter Zijlstra
2019-03-07 18:51           ` hpa
2019-03-07 19:03           ` Peter Zijlstra
2019-03-08 15:01             ` Josh Poimboeuf
2019-03-08 15:07               ` Peter Zijlstra
2019-03-07 20:23           ` Peter Zijlstra
2019-03-07 20:40             ` Peter Zijlstra
2019-03-08 15:07               ` Josh Poimboeuf
2019-03-08 15:23                 ` Peter Zijlstra
2019-03-07 20:15       ` Andrey Ryabinin
2019-03-07 20:33         ` Peter Zijlstra
2019-03-07 20:40           ` Andrey Ryabinin
2019-03-07 20:42           ` Peter Zijlstra
2019-03-08 21:02   ` Josh Poimboeuf
2019-03-08 21:31     ` Peter Zijlstra
2019-03-08 21:54       ` Josh Poimboeuf
2019-03-10 13:10     ` Peter Zijlstra
2019-03-11 18:01       ` Josh Poimboeuf
2019-03-07 11:45 ` [PATCH 19/20] objtool: uaccess PUSHF/POPF support Peter Zijlstra
2019-03-08 21:11   ` Josh Poimboeuf
2019-03-10 13:12     ` Peter Zijlstra
2019-03-07 11:45 ` [PATCH 20/20] objtool: Add Direction Flag validation Peter Zijlstra
2019-03-08 21:16   ` Josh Poimboeuf
2019-03-08 21:33     ` Peter Zijlstra
2019-03-08 21:56       ` Josh Poimboeuf
2019-03-10 13:13         ` Peter Zijlstra
2019-03-11 18:00           ` Josh Poimboeuf
2019-03-07 12:03 ` [PATCH 00/20] objtool: UACCESS validation v3 Peter Zijlstra
2019-03-07 12:55   ` Peter Zijlstra
2019-03-07 13:13     ` Peter Zijlstra
2019-03-07 16:47       ` Josh Poimboeuf
2019-03-07 16:50         ` Josh Poimboeuf
2019-03-07 17:00         ` Linus Torvalds
2019-03-07 17:17           ` Josh Poimboeuf
2019-03-07 17:38             ` Peter Zijlstra
2019-03-07 17:45               ` Linus Torvalds
2019-03-07 18:18                 ` Steven Rostedt
2019-03-10 13:16                   ` Peter Zijlstra [this message]
2019-04-19 10:08                     ` [PATCH] compiler.h, tracing: Remove CONFIG_PROFILE_ALL_BRANCHES Ingo Molnar
2019-04-19 13:04                       ` Steven Rostedt
2019-03-07 17:04         ` [PATCH 00/20] objtool: UACCESS validation v3 hpa
2019-03-07 17:18           ` Josh Poimboeuf
2019-03-07 17:29             ` hpa
2019-03-07 17:45               ` Josh Poimboeuf
2019-03-07 17:48                 ` Linus Torvalds
2019-03-07 17:43         ` Peter Zijlstra
2019-03-07 17:48           ` Josh Poimboeuf
2019-04-03  8:21             ` [tip:core/objtool] tracing: Improve "if" macro code generation tip-bot for Josh Poimboeuf
2019-03-07 16:31   ` [PATCH 00/20] objtool: UACCESS validation v3 Linus Torvalds
2019-03-07 17:14 ` hpa

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