lkml.org 
[lkml]   [2011]   [Aug]   [8]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
    Patch in this message
    /
    Date
    From
    SubjectRe: [PATCH 4/5] writeback: per task dirty rate limit
    On Mon, Aug 08, 2011 at 09:47:14PM +0800, Peter Zijlstra wrote:
    > On Sat, 2011-08-06 at 16:44 +0800, Wu Fengguang wrote:
    > > Add two fields to task_struct.
    > >
    > > 1) account dirtied pages in the individual tasks, for accuracy
    > > 2) per-task balance_dirty_pages() call intervals, for flexibility
    > >
    > > The balance_dirty_pages() call interval (ie. nr_dirtied_pause) will
    > > scale near-sqrt to the safety gap between dirty pages and threshold.
    > >
    > > XXX: The main problem of per-task nr_dirtied is, if 10k tasks start
    > > dirtying pages at exactly the same time, each task will be assigned a
    > > large initial nr_dirtied_pause, so that the dirty threshold will be
    > > exceeded long before each task reached its nr_dirtied_pause and hence
    > > call balance_dirty_pages().
    > >
    > > Signed-off-by: Wu Fengguang <fengguang.wu@intel.com>
    > > ---
    > > include/linux/sched.h | 7 ++
    > > mm/memory_hotplug.c | 3 -
    > > mm/page-writeback.c | 106 +++++++++-------------------------------
    > > 3 files changed, 32 insertions(+), 84 deletions(-)
    >
    > No fork() hooks? This way tasks inherit their parent's dirty count on
    > clone().

    Ah good point. Here is the quick fix.

    Thanks,
    Fengguang
    ---

    --- linux-next.orig/kernel/fork.c 2011-08-08 22:11:59.000000000 +0800
    +++ linux-next/kernel/fork.c 2011-08-08 22:18:05.000000000 +0800
    @@ -1301,6 +1301,9 @@ static struct task_struct *copy_process(
    p->pdeath_signal = 0;
    p->exit_state = 0;

    + p->nr_dirtied = 0;
    + p->nr_dirtied_pause = 8;
    +
    /*
    * Ok, make it visible to the rest of the system.
    * We dont wake it up yet.

    \
     
     \ /
      Last update: 2011-08-08 16:23    [W:0.020 / U:2.676 seconds]
    ©2003-2016 Jasper Spaans. hosted at Digital OceanAdvertise on this site