Jonathan T. Looney jtl at freebsd.org wrote on
Thu Jun 7 03:00:00 UTC 2018 :
> I believe the theory is that the compiler (remember, this is
> __builtin_memset) can optimize away portions of the zeroing, or can
> optimize zeroing for small sizes.
>
> For example, imagine you do this:
>
> stru
-Original Message-
From: Brooks Davis
Date: 2018-06-07, Thursday at 09:27
To: Ravi Pokala
Cc: "Jonathan T. Looney" , Mateusz Guzik ,
Mateusz Guzik , src-committers ,
,
Subject: Re: svn commit: r334702 - head/sys/sys
> On Thu, Jun 07, 2018 at 12:01:00AM -0400, Ravi Pokala
On Thu, Jun 07, 2018 at 12:01:00AM -0400, Ravi Pokala wrote:
> > I believe the theory is that the compiler (remember, this is
> > __builtin_memset) can optimize away portions of the zeroing, or can
> > optimize zeroing for small sizes.
>
> Ahhh! I didn't consider that the compiler would be doing
ipping zeroing parts that are set immediately after
the call.
Thanks!
-Ravi (rpokala@)
-Original Message-
From: "Jonathan T. Looney"
Date: 2018-06-06, Wednesday at 22:58
To: Ravi Pokala
Cc: Mateusz Guzik , Mateusz Guzik ,
src-committers , ,
Subject: Re: svn commit: r334702
, , <
svn-src-head@freebsd.org>
> Subject: Re: svn commit: r334702 - head/sys/sys
>
> > On Wed, Jun 6, 2018 at 1:35 PM, Ravi Pokala wrote:
> >
> >>> + * Passing the flag down requires malloc to blindly zero the entire
object.
> >>> + * In practice a lot
-Original Message-
From: on behalf of Mateusz Guzik
Date: 2018-06-06, Wednesday at 09:01
To: Ravi Pokala
Cc: Mateusz Guzik , src-committers
, ,
Subject: Re: svn commit: r334702 - head/sys/sys
> On Wed, Jun 6, 2018 at 1:35 PM, Ravi Pokala wrote:
>
>>> + * Passin
Hi Ben, Ravi,
GCC/Clang are fine with the just curly braces, or just do/while(0).
The core benefit of the ({ }) syntax is to allow multiple-statement
macros to have expression syntax externally (i.e., yield a value) —
which is not possible in standard C due to concession to simplistic
parsers. B
-Original Message-
From: on behalf of Benjamin Kaduk
Date: 2018-06-06, Wednesday at 07:40
To: Ravi Pokala
Cc: Mateusz Guzik , src-committers
, ,
Subject: Re: svn commit: r334702 - head/sys/sys
> On Wed, Jun 6, 2018 at 6:35 AM, Ravi Pokala wrote:
>>
>
On Wed, Jun 6, 2018 at 1:35 PM, Ravi Pokala wrote:
> > + * Passing the flag down requires malloc to blindly zero the entire
> object.
> > + * In practice a lot of the zeroing can be avoided if most of the object
> > + * gets explicitly initialized after the allocation. Letting the
> compiler
> >
On Wed, 6 Jun 2018, Benjamin Kaduk wrote:
On Wed, Jun 6, 2018 at 6:35 AM, Ravi Pokala wrote:
Hi Mateusz,
...
...
#ifdef _KERNEL
#define malloc(size, type, flags) ({
\
Now that I'm taking another look at this, I'm confused as to why the
entire macro expansion is inside parenthe
On Wed, Jun 6, 2018 at 6:35 AM, Ravi Pokala wrote:
> Hi Mateusz,
>
> -Original Message-
> From: on behalf of Mateusz Guzik
>
> Date: 2018-06-06, Wednesday at 01:08
> To: , , <
> svn-src-head@freebsd.org>
> Subject: svn commit: r334702 - head/sys/sys
>
> > ...
> > #ifdef _KERNEL
> > #
Hi Mateusz,
-Original Message-
From: on behalf of Mateusz Guzik
Date: 2018-06-06, Wednesday at 01:08
To: , ,
Subject: svn commit: r334702 - head/sys/sys
> Author: mjg
> Date: Wed Jun 6 05:08:05 2018
> New Revision: 334702
> URL: https://svnweb.freebsd.org/changeset/base/334702
>
>
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