lkml.org 
[lkml]   [2009]   [Nov]   [2]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
    /
    Date
    SubjectRe: [RFC][-mm][PATCH 1/6] oom-killer: updates for classification of OOM
    From
    Thanks! your review is very helpful around NUMA.

    Christoph Lameter wrote:
    > On Mon, 2 Nov 2009, KAMEZAWA Hiroyuki wrote:
    >
    >> /*
    >> - * Types of limitations to the nodes from which allocations may occur
    >> + * Types of limitations to zones from which allocations may occur
    >> */
    >
    > "Types of limitations that may cause OOMs"? MEMCG limitations are not zone
    > based.
    >
    ah, will rewrite.

    >> */
    >>
    >> -unsigned long badness(struct task_struct *p, unsigned long uptime)
    >> +static unsigned long __badness(struct task_struct *p,
    >> + unsigned long uptime, enum oom_constraint constraint,
    >> + struct mem_cgroup *mem)
    >> {
    >> unsigned long points, cpu_time, run_time;
    >> struct mm_struct *mm;
    >
    > Why rename this function? You are adding a global_badness anyways.
    >
    just because of history of my own updates...i.e. mistake.
    no reason. sorry.

    >
    >> + /*
    >> + * In numa environ, almost all allocation will be against NORMAL zone.
    >
    > The typical allocations will be against the policy_zone! SGI IA64 (and
    > others) have policy_zone == GFP_DMA.
    >
    Hmm ? ok. I thought GPF_DMA for ia64 was below 4G zone.
    If all memory are GFP_DMA(as ppc), that means no lowemem.
    I'll just rewrite above comments as
    "typical allocation will be against policy_zone".


    >> + * But some small area, ex)GFP_DMA for ia64 or GFP_DMA32 for x86-64
    >> + * can cause OOM. We can use policy_zone for checking lowmem.
    >> + */
    >
    > Simply say that we are checking if the zone constraint is below the policy
    > zone?
    >
    ok, will rewrite. Too verbose just bacause policy_zone isn't well unknown.


    >> + * Now, only mempolicy specifies nodemask. But if nodemask
    >> + * covers all nodes, this oom is global oom.
    >> + */
    >> + if (nodemask && !nodes_equal(node_states[N_HIGH_MEMORY], *nodemask))
    >> + ret = CONSTRAINT_MEMORY_POLICY;
    >
    > Huh? A cpuset can also restrict the nodes?
    >
    cpuset doesn't pass nodemask for allocation(now).
    It checks its nodemask in get_free_page_from_freelist(), internally.

    >> + /*
    >> + * If not __GFP_THISNODE, zonelist containes all nodes. And if
    >
    > Dont see any __GFP_THISNODE checks here.
    >
    If __GFP_THISNODE, zonelist includes local node only. Then zonelist/nodemask
    check will hunt it and result will be CONSTRAINT_MEMPOLICY.
    Then...hum....recommending CONSTRAINT_THISNODE ?

    >> panic("out of memory from page fault. panic_on_oom is selected.\n");
    >>
    >> read_lock(&tasklist_lock);
    >> - __out_of_memory(0, 0); /* unknown gfp_mask and order */
    >> + /*
    >> + * Considering nature of pages required for page-fault,this must be
    >> + * global OOM (if not cpuset...). Then, CONSTRAINT_NONE is correct.
    >> + * zonelist, nodemasks are unknown...
    >> + */
    >> + __out_of_memory(0, CONSTRAINT_NONE, 0, NULL);
    >> read_unlock(&tasklist_lock);
    >
    > Page faults can occur on processes that have memory restrictions.
    >
    yes. comments are bad. will rewrite. But we don't have any useful
    information here.Fixing pagefault_out_of_memory is on my to-do-list.
    It seems wrong.

    But a condition unclear to me is when VM_FAULT_OOM can be returned
    without oom-kill...so plz give me time.

    Thanks,
    -Kame




    \
     
     \ /
      Last update: 2009-11-03 00:05    [W:0.097 / U:0.008 seconds]
    ©2003-2016 Jasper Spaans. hosted at Digital OceanAdvertise on this site