On Mon, Feb 24, 2014 at 07:03:12PM +0200, Imre Deak wrote: > On Thu, 2014-02-20 at 11:51 -0800, Ben Widawsky wrote: > > The previous allocation mechanism would get 2 contiguous allocations, > > one for the page directories, and one for the page tables. As each page > > table is 1 page, and there are 512 of these per page directory, this > > goes to 2MB. An unfriendly request at best. Worse still, our HW now > > supports 4 page directories, and a 2MB allocation is not allowed. > > > > In order to fix this, this patch attempts to split up each page table > > allocation into a single, discrete allocation. There is nothing really > > fancy about the patch itself, it just has to manage an extra pointer > > indirection, and have a fancier bit of logic to free up the pages. > > > > To accommodate some of the added complexity, two new helpers are > > introduced to allocate, and free the page table pages. > > > > NOTE: I really wanted to split the way we do allocations, and the way in > > which we identify the page table/page directory being used. I found > > splitting this functionality up to be too unwieldy. I apologize in > > advance to the reviewer. I'd recommend looking at the result, rather > > than the diff. > > > > v2/NOTE2: This patch predated commit: > > 6f1cc993518462ccf039e195fabd47e7aa5bfd13 > > Author: Chris Wilson <chris@xxxxxxxxxxxxxxxxxx> > > Date: Tue Dec 31 15:50:31 2013 +0000 > > > > drm/i915: Avoid dereference past end of page arr > > > > It fixed the same issue as that patch, but because of the limbo state of > > PPGTT, Chris patch was merged instead. The excess churn is a result of > > my using my original patch, which has my preferred naming. Primarily > > act_* is changed to which_*, but it's mostly the same otherwise. I've > > kept the convention Chris used for the pte wrap (I had something > > slightly different, and broken - but fixable) > > > > v3: Rename which_p[..]e to drop which_ (Chris) > > Remove BUG_ON in inner loop (Chris) > > Redo the pde/pdpe wrap logic (Chris) > > > > v4: s/1MB/2MB in commit message (Imre) > > Plug leaking gen8_pt_pages in both the error path, as well as general > > free case (Imre) > > > > v5: Rename leftover "which_" variables (Imre) > > Add the pde = 0 wrap that was missed from v3 (Imre) > > > > Reviewed-by: Imre Deak <imre.deak@xxxxxxxxx> > > Signed-off-by: Ben Widawsky <ben@xxxxxxxxxxxx> > > Reviewed-by: Imre Deak <imre.deak@xxxxxxxxx> > Thanks very much for your thorough review of the series. -- Ben Widawsky, Intel Open Source Technology Center _______________________________________________ Intel-gfx mailing list Intel-gfx@xxxxxxxxxxxxxxxxxxxxx http://lists.freedesktop.org/mailman/listinfo/intel-gfx
