[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]
Message-Id: <20060803000331.22fcb4c0.akpm@osdl.org>
Date: Thu, 3 Aug 2006 00:03:31 -0700
From: Andrew Morton <akpm@...l.org>
To: Jay Lan <jlan@...r.sgi.com>
Cc: linux-kernel@...r.kernel.org, nagar@...son.ibm.com,
balbir@...ibm.com, jes@....com, csturtiv@....com, tee@....com,
guillaume.thouvenin@...l.net
Subject: Re: [patch 3/3] convert CONFIG tag for extended accounting routines
On Wed, 02 Aug 2006 21:23:35 -0700
Jay Lan <jlan@...r.sgi.com> wrote:
> +/**
> + * acct_update_integrals - update mm integral fields in task_struct
> + * @tsk: task_struct for accounting
> + */
> +void acct_update_integrals(struct task_struct *tsk)
> +{
> + if (likely(tsk->mm)) {
> + long delta =
> + cputime_to_jiffies(tsk->stime) - tsk->acct_stimexpd;
If a 32 architecture chooses to implement a 64-bit cputime_t, this
expression might go wrong for very long-running tasks and high HZ.
Perhaps we should do all this in terms of cputime_t and export everything
to userspace as u64?
> + if (delta == 0)
> + return;
> + tsk->acct_stimexpd = tsk->stime;
> + tsk->acct_rss_mem1 += delta * get_mm_rss(tsk->mm);
> + tsk->acct_vm_mem1 += delta * tsk->mm->total_vm;
It's a bit weird to be multiplying RSS by time. What unit is a "byte
second"?
If this is not a bug then I guess this is an intermediate term for
additional downstream processing. There is information loss here and I'd
have thought that it would be better to simply send `delta' and the rss
straight to userspace, let userspace work out what math it wants to perform
on it. If that makes sense?
I see that the code has been like this for a long time, so treat this as a
"please educate me about BSD accounting" email ;)
-
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/
Powered by blists - more mailing lists