linux-kernel - Re: [PATCH 3/4] x86: Rewrite switch

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Message-ID: <20160615080327.GA15894@gmail.com>
Date:	Wed, 15 Jun 2016 10:03:27 +0200
From:	Ingo Molnar <mingo@...nel.org>
To:	Andy Lutomirski <luto@...capital.net>
Cc:	Brian Gerst <brgerst@...il.com>, X86 ML <x86@...nel.org>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	"H. Peter Anvin" <hpa@...or.com>,
	Denys Vlasenko <dvlasenk@...hat.com>,
	Borislav Petkov <bp@...e.de>,
	Thomas Gleixner <tglx@...utronix.de>
Subject: Re: [PATCH 3/4] x86: Rewrite switch_to() code


* Andy Lutomirski <luto@...capital.net> wrote:

> On Sat, May 21, 2016 at 9:04 AM, Brian Gerst <brgerst@...il.com> wrote:
>
> > Move the low-level context switch code to an out-of-line asm stub instead of 
> > using complex inline asm.  This allows constructing a new stack frame for the 
> > child process to make it seamlessly flow to ret_from_fork without an extra 
> > test and branch in __switch_to().  It also improves code generation for 
> > __schedule() by using the C calling convention instead of clobbering all 
> > registers.
> 
> Just a heads up: I'm writing some code that conflicts with this patch. The 
> conflict will be easy to resolve, and, if this patch beats mine to -tip, I'll 
> rebase.

So I was expecting another iteration of this switch_to() series, but had no 
fundamental objections to the concept.

Thanks,

	Ingo