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Message-ID: <44D24500.7060107@sgi.com>
Date: Thu, 03 Aug 2006 11:48:32 -0700
From: Jay Lan <jlan@....com>
To: Shailabh Nagar <nagar@...son.ibm.com>
Cc: Andrew Morton <akpm@...l.org>, Jay Lan <jlan@...r.sgi.com>,
linux-kernel@...r.kernel.org, balbir@...ibm.com, jes@....com,
csturtiv@....com, tee@....com, guillaume.thouvenin@...l.net
Subject: Re: [patch 1/3] basic accounting over taskstats
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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