Date: Mon, 7 Mar 2005 11:51:56 -0800 From: "David O'Brien" <obrien@FreeBSD.org> To: Scott Long <scottl@samsco.org> Cc: John Baldwin <jhb@FreeBSD.org> Subject: Re: cvs commit: src/sys/kern kern_sig.c Message-ID: <20050307195156.GA18850@dragon.nuxi.com> In-Reply-To: <422719E0.10703@samsco.org> References: <200503021343.j22DhpQ3075008@repoman.freebsd.org> <200503020915.28512.jhb@FreeBSD.org> <4226446B.7020406@freebsd.org> <61ac46c154aa515a692308440dd1141d@FreeBSD.org> <422710DD.1070203@freebsd.org> <422719E0.10703@samsco.org>
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On Thu, Mar 03, 2005 at 07:06:24AM -0700, Scott Long wrote:
> a bit. Also, there is talk about increasing the default kstack size due
> to all of the extra inlining that the compiler does with the -O2 option
I'd love more details on the extra inlining people are seeing with -O2.
(i.e. specifics) -O2 is not supose to do extra function inlining. That
is suppose to be a -O3 thing.
>From the GCC manual:
-O3 Optimize yet more.
-O3 turns on all optimizations specified by -O2 and also turns on the
-finline-functions, -fweb and -frename-registers options.
-O2 Optimize even more.
GCC performs nearly all supported optimizations that do not involve a
space-speed tradeoff. The compiler does not perform loop unrolling or
function inlining when you specify -O2. As compared to -O, this
option increases both compilation time and the performance of the
generated code.
..snip..
The -O2 options that affect size are:
-falign-functions -falign-jumps -falign-loops -falign-labels
-freorder-blocks -fprefetch-loop-arrays
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