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    SubjectRe: [RFC][PATCH 8/8] RSS controller support reclamation
    Balbir Singh wrote:


    >> And what about a hard limit - how would you fail in page fault in
    >> case of limit hit? SIGKILL/SEGV is not an option - in this case we
    >> should run synchronous reclamation. This is done in beancounter
    >> patches v6 we've sent recently.
    > I thought about running synchronous reclamation, but then did not follow
    > that approach, I was not sure if calling the reclaim routines from the
    > page fault context is a good thing to do. It's worth trying out, since

    Each page fault potentially calls reclamation by allocating
    required page with __GFP_IO | __GFP_FS bits set. Synchronous
    reclamation in page fault is really normal.


    >> Please correct me if I'm wrong, but does this reclamation work like
    >> "run over all the zones' lists searching for page whose controller
    >> is sc->container" ?
    > Yeah, that's correct. The code can also reclaim memory from all over-the-limit

    OK. What if I have a container with 100 pages limit in a 4Gb
    (~ million of pages) machine and this group starts reclaiming
    its pages. In case this group uses its pages heavily they will
    be at the beginning of an LRU list and reclamation code would
    have to scan through all (million) pages before it finds proper
    ones. This is not optimal!

    > containers (by passing SC_OVERLIMIT_ALL). The idea behind using such a scheme
    > is to ensure that the global LRU list is not broken.

    isolate_lru_pages() helps in this. As far as I remember this
    was introduced to reduce lru lock contention and keep lru
    lists integrity.

    In beancounters patches this is used to shrink BC's pages.
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      Last update: 2006-11-10 10:37    [W:0.021 / U:112.884 seconds]
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