From: Linus Torvalds <torvalds@linux-foundation.org>
To: Rasmus Villemoes <linux@rasmusvillemoes.dk>
Cc: Luis Chamberlain <mcgrof@kernel.org>,
Andrew Morton <akpm@linux-foundation.org>,
Jessica Yu <jeyu@kernel.org>, Borislav Petkov <bp@alien8.de>,
Jonathan Corbet <corbet@lwn.net>,
Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
Nick Desaulniers <ndesaulniers@google.com>
Subject: Re: [PATCH v2 1/2] init/initramfs.c: allow asynchronous unpacking
Date: Thu, 11 Mar 2021 10:02:27 -0800 [thread overview]
Message-ID: <CAHk-=wjiNDC9QAnVGS9w9enXiErHJLdm6982VJAZFmNoPH-AEg@mail.gmail.com> (raw)
In-Reply-To: <2a8c6ceb-9dda-f8b6-1a96-6e75dd3b4eea@rasmusvillemoes.dk>
On Wed, Mar 10, 2021 at 5:45 PM Rasmus Villemoes
<linux@rasmusvillemoes.dk> wrote:
>
> Hm, gcc does elide the test of the return value, but jumps back to a
> place where it always loads state from its memory location and does the
> whole switch(). To get it to jump directly to the code implementing the
> various do_* helpers it seems one needs to avoid that global variable
> and instead return the next state explicitly. The below boots, but I
> still can't see any measurable improvement on ppc.
Ok. That's definitely the right way to do efficient statemachines that
the compiler can actually generate ok code for, but if you can't
measure the difference I guess it isn't even worth doing.
Thanks for checking, though.
Linus
next prev parent reply other threads:[~2021-03-11 18:03 UTC|newest]
Thread overview: 21+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-02-24 14:29 [PATCH/RFC 0/2] background initramfs unpacking, and CONFIG_MODPROBE_PATH Rasmus Villemoes
2021-02-24 14:29 ` [PATCH/RFC 1/2] init/initramfs.c: allow asynchronous unpacking Rasmus Villemoes
2021-02-24 17:17 ` Linus Torvalds
2021-02-24 22:13 ` Rasmus Villemoes
2021-03-02 16:26 ` Luis Chamberlain
2021-02-24 14:29 ` [PATCH/RFC 2/2] modules: add CONFIG_MODPROBE_PATH Rasmus Villemoes
2021-02-24 22:19 ` [PATCH/RFC 0/2] background initramfs unpacking, and CONFIG_MODPROBE_PATH Rasmus Villemoes
2021-03-09 21:16 ` [PATCH v2 " Rasmus Villemoes
2021-03-09 21:16 ` [PATCH v2 1/2] init/initramfs.c: allow asynchronous unpacking Rasmus Villemoes
2021-03-09 22:07 ` Linus Torvalds
2021-03-09 22:39 ` Rasmus Villemoes
2021-03-11 17:55 ` Luis Chamberlain
2021-03-09 22:16 ` Linus Torvalds
2021-03-09 22:51 ` Rasmus Villemoes
2021-03-11 0:17 ` Rasmus Villemoes
2021-03-11 1:45 ` Rasmus Villemoes
2021-03-11 18:02 ` Linus Torvalds [this message]
2021-03-13 13:13 ` Rasmus Villemoes
2021-03-09 21:17 ` [PATCH v2 2/2] modules: add CONFIG_MODPROBE_PATH Rasmus Villemoes
2021-03-10 9:46 ` Greg Kroah-Hartman
2021-03-11 13:28 ` Jessica Yu
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