From: Chuck Ebbert <76306.1226@compuserve.com>
To: Linus Torvalds <torvalds@osdl.org>
Cc: Andrew Morton <akpm@osdl.org>,
linux-kernel <linux-kernel@vger.kernel.org>
Subject: Re: [patch] i386: use C code for current_thread_info()
Date: Sun, 11 Jun 2006 16:43:36 -0400 [thread overview]
Message-ID: <200606111647_MC3-1-C228-993B@compuserve.com> (raw)
In-Reply-To: <Pine.LNX.4.64.0606111225380.5498@g5.osdl.org>
On Sun, 11 Jun 2006 12:33:10 -0700, Linus Torbalds wrote:
> On Sun, 11 Jun 2006, Chuck Ebbert wrote:
> >
> > Using C code for current_thread_info() lets the compiler optimize it.
>
> Ok, me likee. I just worry that this might break some older gcc version.
> Have you checked with gcc-3.2 or something?
I just tried gcc 3.3.3 and the kernel gets a little bigger but it boots
and runs OK. That's the oldest compiler I can find.
text data bss dec hex filename
3593627 559864 342728 4496219 449b5b 2.6.17-rc6-32-post/vmlinux
3591371 559864 342728 4493963 44928b 2.6.17-rc6-32/vmlinux
+2256
Looking at the generated code, it seems the compiler just makes dumb
choices and tends to recompute current_thread_info() in unlikely code
paths even when there is no register pressure. 4.0.2 makes better
choices.
--
Chuck
next reply other threads:[~2006-06-11 20:48 UTC|newest]
Thread overview: 15+ messages / expand[flat|nested] mbox.gz Atom feed top
2006-06-11 20:43 Chuck Ebbert [this message]
2006-06-11 21:05 ` Emmanuel Fleury
-- strict thread matches above, loose matches on Subject: below --
2006-06-13 5:26 Albert Cahalan
2006-06-13 1:50 Chuck Ebbert
2006-06-13 6:43 ` Andreas Mohr
2006-06-13 9:27 ` Avi Kivity
2006-06-12 17:14 Chuck Ebbert
2006-06-12 17:55 ` Adrian Bunk
2006-06-12 18:48 ` Andreas Mohr
2006-06-11 19:07 Chuck Ebbert
2006-06-11 19:33 ` Linus Torvalds
2006-06-11 19:42 ` Jan Engelhardt
2006-06-11 20:33 ` Jan Engelhardt
2006-06-11 20:44 ` Alistair John Strachan
2006-06-12 8:10 ` Andi Kleen
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