Re: [PATCH] task_struct: remove writeonly counters

[Andrew Morton <akpm@osdl.org>]

On Tue, 1 Aug 2006 06:29:51 +0400
Alexey Dobriyan <adobriyan@gmail.com> wrote:

> ...
>
> +++ b/include/linux/sched.h
> @@ -962,8 +962,6 @@ #endif
>   * to a stack based synchronous wait) if its doing sync IO.
>   */
>  	wait_queue_t *io_wait;
> -/* i/o counters(bytes read/written, #syscalls */
> -	u64 rchar, wchar, syscr, syscw;

This is kinda funny.  These fields were added a year and a half ago, with
the intention that the info be made available to userspace.  But then
things got horridly stuck.  It's only in the past couple of weeks that we've
gained appropriate reporting-to-userspace infrastructure to be able to use
these fields.

And lo, on the very day when you propose removing these fields, Jay posts a
new patchset ("add CSA accounting to taskstats") which finally gets around to
using them.

So..  we should keep these fields for now - we can perhaps remove them (in
less than 1.5 years) if for some reason the CSA patches crash and burn (I
don't think they will).