lkml.org 
[lkml]   [2022]   [Jun]   [8]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
    /
    Date
    SubjectRe: [PATCH v5 2/9] mm/demotion: Expose per node memory tier to sysfs
    From
    On 6/8/22 9:36 PM, Tim Chen wrote:
    > On Wed, 2022-06-08 at 10:25 +0530, Aneesh Kumar K V wrote:
    >> On 6/8/22 1:45 AM, Tim Chen wrote:
    >>> On Fri, 2022-06-03 at 19:12 +0530, Aneesh Kumar K.V wrote:
    >>>>
    >>>> +static struct memory_tier *__node_get_memory_tier(int node)
    >>>> +{
    >>>> + struct memory_tier *memtier;
    >>>> +
    >>>> + list_for_each_entry(memtier, &memory_tiers, list) {
    >>>
    >>> We could need to map node to mem_tier quite often, if we need
    >>> to account memory usage at tier level. It will be more efficient
    >>> to have a pointer from node (pgdat) to memtier rather
    >>> than doing a search through the list.
    >>>
    >>>
    >>
    >> That is something I was actively trying to avoid. Currently all struct
    >> memory_tier references are with memory_tier_lock mutex held. That
    >> simplify the locking and reference counting.
    >>
    >> As of now we are able to implement all the required interfaces without
    >> pgdat having pointers to struct memory_tier. We can update pgdat with
    >> memtier details when we are implementing changes requiring those. We
    >> could keep additional memtier->dev reference to make sure memory tiers
    >> are not destroyed while other part of the kernel is referencing the
    >> same. But IMHO such changes should wait till we have users for the same.
    >>
    >
    > I think we should have an efficient mapping from node to memtier from
    > the get go. There are many easily envisioned scenarios where
    > we need to map from node to memtier, which Ying pointed out.
    >

    I did an initial implementation here. We need to make sure we can access
    NODE_DATA()->memtier lockless. Can you review the changes here

    https://lore.kernel.org/linux-mm/87sfoffcfz.fsf@linux.ibm.com

    -aneesh

    \
     
     \ /
      Last update: 2022-06-08 18:16    [W:2.878 / U:1.372 seconds]
    ©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site