Messages in this thread | | | Date | Mon, 18 Apr 2011 18:15:10 -0700 (PDT) | From | David Rientjes <> | Subject | Re: [PATCH incremental] cpusets: initialize spread rotor lazily |
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On Mon, 18 Apr 2011, Michal Hocko wrote:
> From: Michal Hocko <mhocko@suse.cz> > Subject: cpusets: initialize spread mem/slab rotor lazily > > Kosaki Motohiro raised a concern that copy_process is hot path and we do > not want to initialize cpuset_{mem,slab}_spread_rotor if they are not > used most of the time. > > I think that we should rather initialize it lazily when rotors are used > for the first time. > This will also catch the case when we set up spread mem/slab later. > > Signed-off-by: Michal Hocko <mhocko@suse.cz> > Reviewed-by: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
Acked-by: David Rientjes <rientjes@google.com>
Thanks Michal!
> Index: linus_tree/kernel/cpuset.c > =================================================================== > --- linus_tree.orig/kernel/cpuset.c 2011-04-18 10:33:15.000000000 +0200 > +++ linus_tree/kernel/cpuset.c 2011-04-18 23:24:02.000000000 +0200 > @@ -2460,11 +2460,19 @@ static int cpuset_spread_node(int *rotor > > int cpuset_mem_spread_node(void) > { > + if (current->cpuset_mem_spread_rotor == NUMA_NO_NODE) > + current->cpuset_mem_spread_rotor = > + node_random(¤t->mems_allowed); > + > return cpuset_spread_node(¤t->cpuset_mem_spread_rotor); > } > > int cpuset_slab_spread_node(void) > { > + if (current->cpuset_slab_spread_rotor == NUMA_NO_NODE) > + current->cpuset_slab_spread_rotor = > + node_random(¤t->mems_allowed); > + > return cpuset_spread_node(¤t->cpuset_slab_spread_rotor); > } > > Index: linus_tree/kernel/fork.c > =================================================================== > --- linus_tree.orig/kernel/fork.c 2011-04-18 10:33:15.000000000 +0200 > +++ linus_tree/kernel/fork.c 2011-04-18 10:33:56.000000000 +0200 > @@ -1126,8 +1126,8 @@ static struct task_struct *copy_process( > mpol_fix_fork_child_flag(p); > #endif > #ifdef CONFIG_CPUSETS > - p->cpuset_mem_spread_rotor = node_random(&p->mems_allowed); > - p->cpuset_slab_spread_rotor = node_random(&p->mems_allowed); > + p->cpuset_mem_spread_rotor = NUMA_NO_NODE; > + p->cpuset_slab_spread_rotor = NUMA_NO_NODE; > #endif > #ifdef CONFIG_TRACE_IRQFLAGS > p->irq_events = 0;
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