From: Peter Zijlstra <a.p.zijlstra@chello.nl>
To: Srivatsa Vaddagiri <vatsa@linux.vnet.ibm.com>
Cc: mingo@kernel.org, pjt@google.com, suresh.b.siddha@intel.com,
efault@gmx.de, linux-kernel@vger.kernel.org
Subject: Re: [RFC][PATCH 1/5] sched, fair: Let minimally loaded cpu balance the group
Date: Wed, 02 May 2012 12:31:30 +0200 [thread overview]
Message-ID: <1335954690.13683.178.camel@twins> (raw)
In-Reply-To: <20120502102541.GA22740@linux.vnet.ibm.com>
On Wed, 2012-05-02 at 15:55 +0530, Srivatsa Vaddagiri wrote:
> * Peter Zijlstra <a.p.zijlstra@chello.nl> [2012-05-01 20:14:31]:
>
> > @@ -3795,12 +3796,11 @@ static inline void update_sg_lb_stats(st
> >
> > /* Bias balancing toward cpus of our domain */
> > if (local_group) {
> > - if (idle_cpu(i) && !first_idle_cpu) {
> > - first_idle_cpu = 1;
> > + load = target_load(i, load_idx);
> > + if (load < balance_load || idle_cpu(i)) {
> > + balance_load = load;
>
> Let's say load_idx != 0 (ex: a busy cpu doing this load balance). In
> that case, for a idle cpu, we could return non-zero load and hence this
> would fail to select such a idle cpu?
Yep, such is the nature of !0 load_idx.
> IOW :
>
> balance_load = 0 iff idle_cpu(i) ??
I think so, even for !0 load_idx, load will only reach zero when we're
idle, just takes longer.
next prev parent reply other threads:[~2012-05-02 10:31 UTC|newest]
Thread overview: 10+ messages / expand[flat|nested] mbox.gz Atom feed top
2012-05-01 18:14 [RFC][PATCH 0/5] various sched and numa bits Peter Zijlstra
2012-05-01 18:14 ` [RFC][PATCH 1/5] sched, fair: Let minimally loaded cpu balance the group Peter Zijlstra
2012-05-02 10:25 ` Srivatsa Vaddagiri
2012-05-02 10:31 ` Peter Zijlstra [this message]
2012-05-02 10:34 ` Srivatsa Vaddagiri
2012-05-04 0:05 ` Suresh Siddha
2012-05-04 16:09 ` Peter Zijlstra
2012-05-01 18:14 ` [RFC][PATCH 2/5] sched, fair: Add some serialization to the sched_domain load-balance walk Peter Zijlstra
2012-05-01 18:14 ` [RFC][PATCH 3/5] x86: Allow specifying node_distance() for numa=fake Peter Zijlstra
2012-05-01 18:14 ` [RFC][PATCH 4/5] x86: Hard partition cpu topology masks on node boundaries Peter Zijlstra
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