linux-kernel - Re: [PATCH v1 5/8] software node: Imply kobj_to

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Message-ID: <CAHp75Vf2h1s-p43q41+Dnw6FP0L-vtb0YkjGHpSdkERYJW6xZw@mail.gmail.com>
Date:   Sun, 28 Mar 2021 15:50:16 +0300
From:   Andy Shevchenko <andy.shevchenko@...il.com>
To:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>
Cc:     Andy Shevchenko <andriy.shevchenko@...ux.intel.com>,
        Daniel Scally <djrscally@...il.com>,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
        Linux Media Mailing List <linux-media@...r.kernel.org>,
        ACPI Devel Maling List <linux-acpi@...r.kernel.org>,
        "Rafael J. Wysocki" <rafael@...nel.org>,
        Yong Zhi <yong.zhi@...el.com>,
        Sakari Ailus <sakari.ailus@...ux.intel.com>,
        Bingbu Cao <bingbu.cao@...el.com>,
        Tianshu Qiu <tian.shu.qiu@...el.com>,
        Mauro Carvalho Chehab <mchehab@...nel.org>,
        Heikki Krogerus <heikki.krogerus@...ux.intel.com>
Subject: Re: [PATCH v1 5/8] software node: Imply kobj_to_swnode() to be no-op

On Sun, Mar 28, 2021 at 11:47 AM Greg Kroah-Hartman
<gregkh@...uxfoundation.org> wrote:
>
> On Sun, Mar 28, 2021 at 12:20:09AM +0200, Andy Shevchenko wrote:
> > Since we don't use structure field layout randomization
> > the manual shuffling can affect some macros, in particular
> > kobj_to_swnode(), which becomes a no-op when kobj member
> > is the first one in the struct swnode.
> >
> > Bloat-o-meter statistics:
> >
> >   add/remove: 0/0 grow/shrink: 2/10 up/down: 9/-100 (-91)
> >   Total: Before=7217, After=7126, chg -1.26%
> >
> > Signed-off-by: Andy Shevchenko <andriy.shevchenko@...ux.intel.com>
> > ---
> >  drivers/base/swnode.c | 2 +-
> >  1 file changed, 1 insertion(+), 1 deletion(-)
> >
> > diff --git a/drivers/base/swnode.c b/drivers/base/swnode.c
> > index 22f81688af2c..ae53c48f84b1 100644
> > --- a/drivers/base/swnode.c
> > +++ b/drivers/base/swnode.c
> > @@ -13,10 +13,10 @@
> >  #include <linux/sysfs.h>
> >
> >  struct swnode {
> > -     int id;
> >       struct kobject kobj;
> >       struct fwnode_handle fwnode;
> >       const struct software_node *node;
> > +     int id;
>
> So you remove one math operation on a pointer and get a 1% size decrease
> of the whole kernel?  Or just one file?

One file, swnode.o. I'll clarify this in the commit message.

-- 
With Best Regards,
Andy Shevchenko