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    SubjectRe: [Intel-gfx] [PATCH] drm/i915: Selectively enable self-reclaim
    Date
    > On Wed, Jun 30, 2010 at 4:07 PM, Linus Torvalds
    > <torvalds@linux-foundation.org> wrote:
    > >
    > > That commit changes the page cache allocation to use
    > >
    > > +                                          mapping_gfp_mask (mapping) |
    > > +                                          __GFP_COLD |
    > > +                                          gfpmask);
    > >
    > > if I read it right. And the default mapping_gfp_mask() is
    > > GFP_HIGHUSER_MOVABLE, so I think you get all of
    > > (__GFP_WAIT | __GFP_IO | __GFP_FS | __GFP_HARDWALL | __GFP_HIGHMEM)
    > > set by default.
    >
    > .. and then I left out the one flag I _meant_ to have there, namely
    > __GFP_MOVABLE.
    >
    > > The old code didn't just play games with ~__GFP_NORETRY and change
    > > that at runtime (which was buggy - no locking, no protection, no
    > > nothing), it also initialized the gfp mask. And that code also got
    > > removed:
    >
    > In fact, I don't really see why we should use that mapping_gfp_mask()
    > at all, since all allocations should be going through that
    > i915_gem_object_get_pages() function anyway. So why not just change
    > that function to ignore the default gfp mask for the mapping, and just
    > use the mask that the o915 driver wants?
    >
    > Btw, why did it want to mark the pages reclaimable?

    I'm not GEM expert at all. but as far as I read following documentation,

    http://lwn.net/Articles/283798/

    GEM memory have pin and unpin state and unpined memory can be reclaimed.
    but it's just guess. So, I wonder if your patch solve the issue. I don't imazine a memory
    state which "swap-out is safe, but compaction is unsafe".

    Dave, if you have good documentation which we understand GEM memory management,
    could you send us?

    - kosaki

    >
    > Anyway, what I'm suggesting somebody who sees this test is just
    > something like the patch below (whitespace-damage - I'm cutting and
    > pasting, it's a trivial one-liner). Does this change any behavior?
    > Vefa?
    >
    > Linus
    >
    > ---
    > diff --git a/drivers/gpu/drm/i915/i915_gem.c b/drivers/gpu/drm/i915/i915_gem.c
    > index 9ded3da..ec8ed6b 100644
    > --- a/drivers/gpu/drm/i915/i915_gem.c
    > +++ b/drivers/gpu/drm/i915/i915_gem.c
    > @@ -2239,7 +2239,7 @@ i915_gem_object_get_pages(struct drm_gem_object *obj,
    > mapping = inode->i_mapping;
    > for (i = 0; i < page_count; i++) {
    > page = read_cache_page_gfp(mapping, i,
    > - mapping_gfp_mask (mapping) |
    > + GFP_HIGHMEM |
    > __GFP_COLD |
    > gfpmask);
    > if (IS_ERR(page))
    > --
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