On Sun, 2007-06-24 at 20:12 -0400, Benjamin LaHaise wrote:
> On Sun, Jun 24, 2007 at 05:09:16PM -0700, Arjan van de Ven wrote:
> > if you care about the last cycle, don't specify -Os but -O2.
> > simple as that... you get what you tell the compiler you want.
>
> Certain distros are shipping kernel
On Sun, Jun 24, 2007 at 05:09:16PM -0700, Arjan van de Ven wrote:
> if you care about the last cycle, don't specify -Os but -O2.
> simple as that... you get what you tell the compiler you want.
Certain distros are shipping kernels compiled with -Os. And it's more
than just a couple of cycles.
On Sun, 2007-06-24 at 19:23 -0400, Benjamin LaHaise wrote:
> On Sun, Jun 24, 2007 at 03:15:17PM -0700, Arjan van de Ven wrote:
> > we should just alias our memset to the __builtin one, and then provide a
> > generic one from lib/ for the cases gcc needs to do a fallback.
>
> The last time I checke
On Sun, Jun 24, 2007 at 03:15:17PM -0700, Arjan van de Ven wrote:
> we should just alias our memset to the __builtin one, and then provide a
> generic one from lib/ for the cases gcc needs to do a fallback.
The last time I checked, gcc generated horrible badly performing code for
builtin memset/m
On Sun, Jun 24, 2007 at 03:15:17PM -0700, Arjan van de Ven wrote:
>
> > > I think all these benefits are the gcc's __builtin_memset optimization
> > > than the explicit call to memset.
> >
> > ... or from complex memset() implementation (some chips even didn't do
> > `rep' fast enough somehow). M
> > I think all these benefits are the gcc's __builtin_memset optimization
> > than the explicit call to memset.
>
> ... or from complex memset() implementation (some chips even didn't do
> `rep' fast enough somehow). Maybe code like below will be acceptable for
> both optimizers and maintainers?
On Sun, Jun 24, 2007 at 08:58:10PM +0800, rae l wrote:
> On 6/23/07, Oleg Verych <[EMAIL PROTECTED]> wrote:
> >Why not just show actual objdump output on code (maybe with different
> >oxygen atoms used in gcc), rather than *talking* about optimization and
> >standards, hm?
> here is the objdump out
On 6/23/07, Oleg Verych <[EMAIL PROTECTED]> wrote:
Why not just show actual objdump output on code (maybe with different
oxygen atoms used in gcc), rather than *talking* about optimization and
standards, hm?
here is the objdump output of the two object files:
As you could see, the older one used
gcc is a C compiler and claims to follow the C standard.
Not with the options the kernel build uses. But, close
enough -- the differences are really minor stuff.
Segher
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On Sat, Jun 23, 2007 at 03:41:26PM +0200, Oleg Verych wrote:
> On Sat, Jun 23, 2007 at 03:13:55PM +0200, Adrian Bunk wrote:
> > On Sat, Jun 23, 2007 at 09:59:33AM +0200, Oleg Verych wrote:
> []
> > > > From: Denis Cheng <[EMAIL PROTECTED]>
> > > >
> > > > the explicit memset call could be optimized
On Sat, Jun 23, 2007 at 03:13:55PM +0200, Adrian Bunk wrote:
> On Sat, Jun 23, 2007 at 09:59:33AM +0200, Oleg Verych wrote:
[]
> > > From: Denis Cheng <[EMAIL PROTECTED]>
> > >
> > > the explicit memset call could be optimized out by data initialization,
> > > thus all the fill working can be done
On Sat, Jun 23, 2007 at 09:59:33AM +0200, Oleg Verych wrote:
> * From: Denis Cheng
> * Newsgroups: linux.kernel
> * Date: Fri, 22 Jun 2007 22:15:49 -0700 (PDT)
>
> > From: Denis Cheng <[EMAIL PROTECTED]>
> >
> > the explicit memset call could be optimized out by data initialization,
> > thus all
* From: Denis Cheng
* Newsgroups: linux.kernel
* Date: Fri, 22 Jun 2007 22:15:49 -0700 (PDT)
> From: Denis Cheng <[EMAIL PROTECTED]>
>
> the explicit memset call could be optimized out by data initialization,
> thus all the fill working can be done by the compiler implicitly.
Can be optimized an
From: Denis Cheng <[EMAIL PROTECTED]>
the explicit memset call could be optimized out by data initialization,
thus all the fill working can be done by the compiler implicitly.
and C standard guaranteed all the unspecified data field initialized to zero.
Signed-off-by: Denis Cheng <[EMAIL PROTECT
On 6/19/07, Jeremy Fitzhardinge <[EMAIL PROTECTED]> wrote:
Denis Cheng wrote:
> From: Denis Cheng <[EMAIL PROTECTED]>
>
> the explicit memset call could be optimized out by data initialization,
> thus all the fill working can be done by the compiler implicitly.
>
How does the generated code chan
On Mon, Jun 18, 2007 at 10:07:21AM -0700, Jeremy Fitzhardinge wrote:
> Denis Cheng wrote:
> > From: Denis Cheng <[EMAIL PROTECTED]>
> >
> > the explicit memset call could be optimized out by data initialization,
> > thus all the fill working can be done by the compiler implicitly.
>
> How does the
Denis Cheng wrote:
> From: Denis Cheng <[EMAIL PROTECTED]>
>
> the explicit memset call could be optimized out by data initialization,
> thus all the fill working can be done by the compiler implicitly.
>
How does the generated code change? Does gcc do something stupid like
statically allocate
On Mon, Jun 18, 2007 at 06:25:17AM -0400, Robert P. J. Day wrote:
>On Mon, 18 Jun 2007, Denis Cheng wrote:
>
>> From: Denis Cheng <[EMAIL PROTECTED]>
>>
>> the explicit memset call could be optimized out by data initialization,
>> thus all the fill working can be done by the compiler implicitly.
>>
On Mon, 18 Jun 2007, Denis Cheng wrote:
> From: Denis Cheng <[EMAIL PROTECTED]>
>
> the explicit memset call could be optimized out by data initialization,
> thus all the fill working can be done by the compiler implicitly.
>
> Signed-off-by: Denis Cheng <[EMAIL PROTECTED]>
>
> ---
> Is there some
From: Denis Cheng <[EMAIL PROTECTED]>
the explicit memset call could be optimized out by data initialization,
thus all the fill working can be done by the compiler implicitly.
Signed-off-by: Denis Cheng <[EMAIL PROTECTED]>
---
Is there some comments on this?
--- arch/x86_64/mm/init.c.orig 2007
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