linux-kernel - Re: [PATCH] trace: reorder struct ring_buffer_per

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite for Android: free password hash cracker in your pocket

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Date:	Thu, 25 Mar 2010 09:38:10 -0400
From:	Steven Rostedt <rostedt@...dmis.org>
To:	Richard Kennedy <richard@....demon.co.uk>
Cc:	Frederic Weisbecker <fweisbec@...il.com>,
	Ingo Molnar <mingo@...hat.com>,
	lkml <linux-kernel@...r.kernel.org>,
	Arnaldo Carvalho de Melo <acme@...radead.org>
Subject: Re: [PATCH] trace: reorder struct ring_buffer_per_cpu to remove
 padding on 64bit

On Thu, 2010-03-25 at 11:27 +0000, Richard Kennedy wrote:
> Reorder structure to remove 8 bytes of padding on 64 bit builds.
> This shrinks the size to 128 bytes so allowing allocation from a smaller
> slab & needed one fewer cache lines.
> 

Thanks!

Just curious, did you use Arnaldo's pahole utility to find this?

-- Steve

> Signed-off-by: Richard Kennedy <richard@....demon.co.uk>
> ----
> patch against 2.6.34-rc2
> compiled & booted on x86_64
> 
> regards
> Richard
> 
> diff --git a/kernel/trace/ring_buffer.c b/kernel/trace/ring_buffer.c
> index 05a9f83..421db5e 100644
> --- a/kernel/trace/ring_buffer.c
> +++ b/kernel/trace/ring_buffer.c
> @@ -422,6 +422,7 @@ int ring_buffer_print_page_header(struct trace_seq
> *s)
>   */
>  struct ring_buffer_per_cpu {
>  	int				cpu;
> +	atomic_t			record_disabled;
>  	struct ring_buffer		*buffer;
>  	spinlock_t			reader_lock;	/* serialize readers */
>  	arch_spinlock_t			lock;
> @@ -439,7 +440,6 @@ struct ring_buffer_per_cpu {
>  	unsigned long			read;
>  	u64				write_stamp;
>  	u64				read_stamp;
> -	atomic_t			record_disabled;
>  };
>  
>  struct ring_buffer {
> 
> 


--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/