Re: [RFC][PATCH] counting bounce pages.

[Andrew Morton <akpm@osdl.org>]

KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com> wrote:
>
> This is a patch for counting bounce pages.
>  With this, pages for bounce buffer is coutned and shown in /proc/meminfo.

As it's purely a debug thing, perhaps /proc/vmstat would be a better place
for displaying this info.

>  Because pages for bounce buffer are not counted in anywhere,
>  sometimes it seems that there are many leaked pages.
>  ex)
>  I found 1.7GB of bounce buffer pages in a crash dump of ia64 kernel,
>  which was passed me to check memory usage. :(

whoops.

>  BTW, I'm not sure whether # of bounce buffer should be includeded in Buffers:
>  of /proc/meminfo.

No, "Buffers:" is "the number of bytes allocated to blockdevice pagecache".
Usually this is filesystem metadata.

>  --- linux-2.6.12-rc2-mm3/fs/proc/proc_misc.c~count_bounce	2005-04-25 12:08:28.000000000 +0900
>  +++ linux-2.6.12-rc2-mm3-kamezawa/fs/proc/proc_misc.c	2005-04-25 16:06:39.000000000 +0900
>  @@ -114,7 +114,7 @@ static int uptime_read_proc(char *page, 
>   
>   	return proc_calc_metrics(page, start, off, count, eof, len);
>   }
>  -
>  +extern atomic_t nr_bounce_pages;

Please always put extern declarations into .h files, with the declaration
visible to the definition and to all users.

>  +		"Bounce :      %8lu kB\n"

There's an unneeded space in there.