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    SubjectRe: TTM page pool allocator
    Jerome Glisse wrote:
    > On Tue, 2009-07-21 at 20:00 +0200, Jerome Glisse wrote:
    >> On Tue, 2009-07-21 at 19:34 +0200, Jerome Glisse wrote:
    >>> On Thu, 2009-06-25 at 17:53 +0200, Thomas Hellström wrote:
    >>>> 4) We could now skip the ttm_tt_populate() in ttm_tt_set_caching, since
    >>>> it will always allocate cached pages and then transition them.
    >>> Okay 4) is bad, what happens (my brain is a bit meltdown so i might be
    >>> wrong) :
    >>> 1 - bo get allocated tt->state = unpopulated
    >>> 2 - bo is mapped few page are faulted tt->state = unpopulated
    >>> 3 - bo is cache transitioned but tt->state == unpopulated but
    >>> they are page which have been touch by the cpu so we need
    >>> to clflush them and transition them, this never happen if
    >>> we don't call ttm_tt_populate and proceed with the remaining
    >>> of the cache transitioning functions
    >>> As a workaround i will try to go through the pages tables and
    >>> transition existing pages. Do you have any idea for a better
    >>> plan ?
    >>> Cheers,
    >>> Jerome
    >> My workaround ruin the whole idea of pool allocation what happens
    >> is that most bo get cache transition page per page. My thinking
    >> is that we should do the following:
    >> - is there is a least one page allocated then fully populate
    >> the object and do cache transition on all the pages.
    >> - otherwise update caching_state and leaves object unpopulated
    >> This needs that we some how reflect the fact that there is at least
    >> one page allocated, i am thinking to adding a new state for that :
    >> ttm_partialy_populated
    >> Thomas what do you think about that ?
    >> Cheers,
    >> Jerome
    > Attached updated patch it doesn't introduce ttm_partialy_populated
    > but keep the populate call in cache transition. So far it seems to
    > work properly on AGP platform and helps quite a lot with performances.
    > I wonder if i should rather allocate some memory to store the pool
    > structure in ttm_page_pool_init rather than having quite a lot of
    > static variables ? Anyone has thought on that ?

    TTM has a device struct per device and an optional global struct that is
    common for all devices and intended to be per subsystem.

    The only subsystem currently having a global structure is the memory
    accounting subsystem:
    struct ttm_mem_global

    You can either put the global stuff there or create and register a
    separate global struct for the page pool.

    I'll probably also later add a global structure for the bo subsystem,
    since we need a common buffer object memory footprint shrinker for
    multiple cards.


    > Cheers,
    > Jerome

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