Re: [patch 1/3] basic accounting over taskstats

[Jay Lan]

Shailabh Nagar wrote:
> Andrew Morton wrote:
>
> > Or we remove this field altogether, perhaps.  The same info is available
> > from /proc/pid/stat anyway.  Is it really needed?
>
> Gathering this data in userspace from /proc might be
> difficult esp. for short-lived tasks.

This is a serious concern. I think increasing TS_COMM_LEN
to 32 would be a good solution.

> Also, /proc may not be mounted ? I'd heard somewhere that
> some sysadmins don't install /proc for security reasons.
> Don't know how far thats true.
>
> Several other fields, totalling 58 bytes, added by the CSA
> patches are also duplicated in /proc/pid/stat. But all of them
> could change in value during the lifetime of a task so I'm
> guessing its not useful to get them from /proc
> even if some kind of userspace polling of the value was
> possible.

The same concern above applies to here, doesn't it?

Regards,
 - jay


> But if there is a way, it would sure save a lot of payload
> sent over taskstats !
>
> "duplicate" fields from CSA:
> +    __u8    ac_nice;        /* task_nice */
> +    char    ac_comm[TS_COMM_LEN];    /* Command name */
> +    __u8    ac_sched;        /* Scheduling discipline */
> +    __u32    ac_pid;            /* Process ID */
> +    __u32    ac_ppid;        /* Parent process ID */
> +    __u64    ac_utime;        /* User CPU time [usec] */
> +    __u64    ac_stime;        /* SYstem CPU time [usec] */
> +    __u64    ac_minflt;        /* Minor Page Fault */
> +    __u64    ac_majflt;        /* Major Page Fault */

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