lkml.org 
[lkml]   [2011]   [Apr]   [18]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
    Patch in this message
    /
    Date
    From
    SubjectRe: [PATCH incremental] cpusets: initialize spread rotor lazily
    On Mon 18-04-11 13:19:09, David Rientjes wrote:
    > On Mon, 18 Apr 2011, Michal Hocko wrote:
    [...]
    > > > Andrew could easily drop the earlier version and merge this v2, but I'm
    > > > asking for selfish reasons:
    > >
    > > Just out of curiosity. What is the reason? Don't want to wait for new mmotm?
    > >
    >
    > Because lazy initialization is another feature on top of the existing
    > patch so it should be done incrementally instead of proposing an entirely
    > new patch which is already mostly in -mm.

    ok, makes sense

    > >
    > > [Here is the follow-up patch based on top of
    > > http://userweb.kernel.org/~akpm/mmotm/broken-out/cpusets-randomize-node-rotor-used-in-cpuset_mem_spread_node.patch]
    > > ---
    > > From: Michal Hocko <mhocko@suse.cz>
    > > Subject: cpusets: initialize spread mem/slab rotor lazily
    > >
    [...]
    > > Also do not use -1 for unitialized nodes and rather use NUMA_NO_NODE
    > > instead.
    > >
    >
    > Don't need to refer to a previous version that used -1 since it will never
    > be committed and nobody will know what you're talking about in the git
    > log.

    removed

    [...]
    > > int cpuset_mem_spread_node(void)
    > > {
    > > + if (current->cpuset_mem_spread_rotor == NUMA_NO_NODE)
    > > + current->cpuset_mem_spread_rotor =
    > > + node_random(&current->mems_allowed);
    > > +
    > > return cpuset_spread_node(&current->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(&current->mems_allowed);
    > > +
    >
    > So one function has the `=' on the line with the assignment (preferred)
    > and the other has it on the new value?

    fixed

    Thanks! Updated patch bellow.

    Changes from v3:
    - code style fix
    Changes from v2:
    - use NUMA_NO_NODE rather than hardcoded -1
    - make the patch incremental to the original one because that one is in
    -mm tree already.
    Changes from v1:
    - initialize cpuset_{mem,slab}_spread_rotor lazily}
    ---
    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>
    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(&current->mems_allowed);
    +
    return cpuset_spread_node(&current->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(&current->mems_allowed);
    +
    return cpuset_spread_node(&current->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;
    --
    Michal Hocko
    SUSE Labs
    SUSE LINUX s.r.o.
    Lihovarska 1060/12
    190 00 Praha 9
    Czech Republic

    \
     
     \ /
      Last update: 2011-04-18 23:31    [W:0.046 / U:0.080 seconds]
    ©2003-2016 Jasper Spaans. hosted at Digital OceanAdvertise on this site