linux-kernel - Re: [RFC PATCH 5/6] x86/alternatives: use temporary mm for text poking

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Date:   Wed, 29 Aug 2018 09:37:13 -0700
From:   Dave Hansen <dave.hansen@...el.com>
To:     Andy Lutomirski <luto@...nel.org>,
        Peter Zijlstra <peterz@...radead.org>
Cc:     Nadav Amit <namit@...are.com>,
        Thomas Gleixner <tglx@...utronix.de>,
        LKML <linux-kernel@...r.kernel.org>,
        Ingo Molnar <mingo@...hat.com>, X86 ML <x86@...nel.org>,
        Arnd Bergmann <arnd@...db.de>,
        linux-arch <linux-arch@...r.kernel.org>,
        Masami Hiramatsu <mhiramat@...nel.org>,
        Kees Cook <keescook@...omium.org>
Subject: Re: [RFC PATCH 5/6] x86/alternatives: use temporary mm for text
 poking

On 08/29/2018 09:32 AM, Andy Lutomirski wrote:
> It's plausible that there are workloads where the current code is
> faster, such as where we're munmapping a single page via syscall and
> we'd prefer to only flush that one TLB entry even if the flush
> operation is slower as a result.

Yeah, I don't specifically remember testing it.  But, I know I wanted to
avoid throwing away thousands of TLB entries when we only want to rid
ourselves of one.