From: Yuyang Du <yuyang.du@intel.com>
To: Peter Zijlstra <peterz@infradead.org>
Cc: mingo@redhat.com, linux-kernel@vger.kernel.org, pjt@google.com,
bsegall@google.com, arjan.van.de.ven@intel.com,
len.brown@intel.com, rafael.j.wysocki@intel.com,
alan.cox@intel.com, mark.gross@intel.com, fengguang.wu@intel.com
Subject: Re: [RESEND PATCH 2/3 v5] sched: Rewrite per entity runnable load average tracking
Date: Wed, 22 Oct 2014 07:39:33 +0800 [thread overview]
Message-ID: <20141021233933.GB2577@intel.com> (raw)
In-Reply-To: <20141021145435.GA23531@worktop.programming.kicks-ass.net>
On Tue, Oct 21, 2014 at 04:54:35PM +0200, Peter Zijlstra wrote:
>
> In the thread here: lkml.kernel.org/r/1409094682.29189.23.camel@j-VirtualBox
> there are concerns about the error bounds of such constructs. We can
> basically 'leak' nr_cpus * threshold, which is potentially a very large
> number.
>
> Do we want to introduce the force updated to combat this?
So introduce a force update here like:
+static inline void update_tg_load_avg(struct cfs_rq *cfs_rq, int force)
...
+ if (force || abs(delta) > cfs_rq->tg_load_avg_contrib / 64) {
That is good. In general, I have been lacking a theory about what threshold
should be concerning overhead vs. accuracy. But I think adding a force here
provides us an option to better comply with the theory if we have it.
Thanks,
Yuyang
next prev parent reply other threads:[~2014-10-22 7:40 UTC|newest]
Thread overview: 18+ messages / expand[flat|nested] mbox.gz Atom feed top
2014-10-10 2:21 [RESEND PATCH 0/3 v5] sched: Rewrite per entity runnable load average tracking Yuyang Du
2014-10-10 2:21 ` [RESEND PATCH 1/3 v5] sched: Remove update_rq_runnable_avg Yuyang Du
2014-10-22 0:23 ` Yuyang Du
2014-10-10 2:21 ` [RESEND PATCH 2/3 v5] sched: Rewrite per entity runnable load average tracking Yuyang Du
2014-10-21 14:32 ` Peter Zijlstra
2014-10-21 23:33 ` Yuyang Du
2014-10-21 14:54 ` Peter Zijlstra
2014-10-21 23:39 ` Yuyang Du [this message]
2014-10-21 14:56 ` Peter Zijlstra
2014-10-22 0:13 ` Yuyang Du
2014-10-22 10:04 ` Peter Zijlstra
2014-10-22 10:28 ` Peter Zijlstra
2014-10-23 11:06 ` Dietmar Eggemann
2014-10-23 11:06 ` Dietmar Eggemann
2014-10-24 1:49 ` Yuyang Du
2014-10-10 2:21 ` [RESEND PATCH 3/3 v5] sched: Remove task and group entity load_avg when they are dead Yuyang Du
2014-10-22 10:31 ` Peter Zijlstra
2014-10-10 10:25 ` [RESEND PATCH 0/3 v5] sched: Rewrite per entity runnable load average tracking Peter Zijlstra
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