linux-kernel - Re: [PATCH v3 0/7] x86: Rewrite switch

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Message-ID: <CA+55aFwb=Lk6xB-gd0eWutu5NM53RX34uAToKaokm5hRRSTsfw@mail.gmail.com>
Date:	Sat, 13 Aug 2016 10:16:03 -0700
From:	Linus Torvalds <torvalds@...ux-foundation.org>
To:	Brian Gerst <brgerst@...il.com>
Cc:	"the arch/x86 maintainers" <x86@...nel.org>,
	Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
	Ingo Molnar <mingo@...nel.org>,
	"H. Peter Anvin" <hpa@...or.com>,
	Denys Vlasenko <dvlasenk@...hat.com>,
	Andy Lutomirski <luto@...capital.net>,
	Borislav Petkov <bp@...e.de>,
	Thomas Gleixner <tglx@...utronix.de>,
	Josh Poimboeuf <jpoimboe@...hat.com>
Subject: Re: [PATCH v3 0/7] x86: Rewrite switch_to()

On Sat, Aug 13, 2016 at 9:38 AM, Brian Gerst <brgerst@...il.com> wrote:
> This patch set simplifies the switch_to() code, by moving the stack switch
> code out of line into an asm stub before calling __switch_to().  This ends
> up being more readable, and using the C calling convention instead of
> clobbering all registers improves code generation.  It also allows newly
> forked processes to construct a special stack frame to seamlessly flow
> to ret_from_fork, instead of using a test and branch, or an unbalanced
> call/ret.

Do you have performance numbers? Is it noticeable/measurable?

             Linus