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From: Linus Torvalds <torvalds@linux-foundation.org>
To: "Luck, Tony" <tony.luck@intel.com>
Cc: Jakub Jelinek <jakub@redhat.com>,
	Segher Boessenkool <segher@kernel.crashing.org>,
	Peter Zijlstra <peterz@infradead.org>,
	Nick Desaulniers <ndesaulniers@google.com>,
	"Eranian, Stephane" <eranian@google.com>,
	"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
	"Chatre, Reinette" <reinette.chatre@intel.com>,
	"Yu, Fenghua" <fenghua.yu@intel.com>,
	"peternewman@google.com" <peternewman@google.com>,
	"james.morse@arm.com" <james.morse@arm.com>,
	"babu.moger@amd.com" <babu.moger@amd.com>,
	"ananth.narayan@amd.com" <ananth.narayan@amd.com>,
	"vschneid@redhat.com" <vschneid@redhat.com>,
	Nathan Chancellor <nathan@kernel.org>,
	clang-built-linux <llvm@lists.linux.dev>,
	Borislav Petkov <bp@alien8.de>, "H. Peter Anvin" <hpa@zytor.com>,
	"linux-toolchains@vger.kernel.org"
	<linux-toolchains@vger.kernel.org>
Subject: Re: [PATCH] x86/resctrl: avoid compiler optimization in __resctrl_sched_in
Date: Tue, 7 Mar 2023 13:14:29 -0800	[thread overview]
Message-ID: <CAHk-=whzzd53rW5Uk0oK7bXVXS_X6sJiisnhrqaz+MkutO7qug@mail.gmail.com> (raw)
In-Reply-To: <SJ1PR11MB6083CADB2B6E859915D456F7FCB79@SJ1PR11MB6083.namprd11.prod.outlook.com>

On Tue, Mar 7, 2023 at 1:11 PM Luck, Tony <tony.luck@intel.com> wrote:
>
> Can you expand about part "a" ... Linux has zillions of static inline functions
> in header files to handle CONFIG options. One version is the real McCoy
> while the other is just a stub for the CONFIG=n case.
>
> What's different about this one?

See the patch I just sent out.

Linux has a lot of "static inline" functions. But that's not at all
what that function was. It was literally just

  static void __resctrl_sched_in(..)

which is disgusting and very wrong.

I hope that compilers then just ignored it ("It's static and not used,
so I'm not generating that code"), and that header file isn't included
in very many places, but it's still very wrong.

               Linus

  reply	other threads:[~2023-03-07 21:22 UTC|newest]

Thread overview: 18+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
     [not found] <20230303231133.1486085-1-eranian@google.com>
     [not found] ` <20230306120106.GE1267364@hirez.programming.kicks-ass.net>
     [not found]   ` <CAKwvOdnRvd5KK01awAyeyt5S36TPPW4_8Z6YL1r4gB-pBrHTbg@mail.gmail.com>
2023-03-07 11:35     ` [PATCH] x86/resctrl: avoid compiler optimization in __resctrl_sched_in Peter Zijlstra
2023-03-07 17:48       ` Linus Torvalds
2023-03-07 18:43       ` Segher Boessenkool
2023-03-07 20:43         ` Jakub Jelinek
2023-03-07 20:54           ` Linus Torvalds
2023-03-07 21:06             ` Linus Torvalds
2023-03-07 21:35               ` Luck, Tony
2023-03-07 21:58                 ` Nick Desaulniers
2023-03-08  6:13               ` Stephane Eranian
2023-03-08 23:25                 ` Linus Torvalds
2023-03-08 16:02               ` Moger, Babu
2023-03-07 21:11             ` Luck, Tony
2023-03-07 21:14               ` Linus Torvalds [this message]
2023-03-07 21:23                 ` Luck, Tony
2023-03-08  0:36                   ` Luck, Tony
2023-03-07 21:16               ` Nick Desaulniers
2023-03-07 21:19                 ` Linus Torvalds
2023-03-07 21:22                   ` Nick Desaulniers

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