linux-kernel - Re: [PATCH] Some love to default profiler

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Date:	Thu, 5 Jul 2007 01:50:27 +0200
From:	"Jesper Juhl" <jesper.juhl@...il.com>
To:	"Alexey Dobriyan" <adobriyan@...il.com>
Cc:	akpm@...l.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH] Some love to default profiler

On 04/07/07, Alexey Dobriyan <adobriyan@...il.com> wrote:
> 1) Drop __KERNEL__ out of profile.h. It contains only internal kernel stuff and
>    not in exported headers list

Even if it's not in the list of exported headers, does it really hurt
to retain that extra safeguard?

> 2) Put profile.c under CONFIG_PROFILING. You enabled profiling in config, you
>    will get it.

Makes logical sense. If the user didn't enable CONFIG_PROFILING why
should she get any profiling related overhead of any kind if we can
avoid it?

> Removes conditional branch from schedule(). Code savings on my
>    usual config:
>
>            text    data     bss     dec     hex filename
>         2921871  179895  180224 3281990  321446 vmlinux         before
>         2920141  179847  180224 3280212  320d54 vmlinux         after
>         --------------------------------------------------------------
>           -1730     -48           -1778
>
Nice savings there. Not that 1.7K is huge, but it's kernel memory is
precious :-)

> 3) Make timer_hook static (hi, Adrian!)

Makes perfect sense to me.

> 4) Convert do {} while (0) into static inline functions

Seems reasonable.

> 5) minor misc stuff
>

One tiny comment below.


> Signed-off-by: Alexey Dobriyan <adobriyan@...il.com>
> ---
>
>  include/linux/profile.h |   78 +++++++++++++++++++++++++-----------------------
>  kernel/Makefile         |    3 +
>  kernel/profile.c        |    2 -
>  3 files changed, 44 insertions(+), 39 deletions(-)
>
[snip]
> +#define prof_on 0
> +static inline void profile_init(void)
> +{
> +}

Just to be pedantic; don't we want a blank line between functions
here, even if they are empty?

> +static inline void profile_tick(int type)
> +{
> +}
> +static inline void profile_hits(int type, void *ip, unsigned int nr_hits)
> +{
> +}
> +static inline void profile_hit(int type, void *ip)
> +{
> +}
> +static inline void profile_munmap(unsigned long addr)
> +{
> +}
> +static inline void profile_task_exit(struct task_struct *tsk)
> +{
> +}
> +static inline int profile_handoff_task(struct task_struct *tsk)
> +{
> +       return 0;
> +}
[snip]

-- 
Jesper Juhl <jesper.juhl@...il.com>
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