On 07/10/2016 10:46, Chris Wilson wrote:A while ago we switched from a contiguous array of pages into an sglist, for that was both more convenient for mapping to hardware and avoided the requirement for a vmalloc array of pages on every object. However, certain GEM API calls (like pwrite, pread as well as performing relocations) do desire access to individual struct pages. A quick hack was to introduce a cache of the last access such that finding the following page was quick - this works so long as the caller desired sequential access. Walking backwards, or multiple callers, still hits a slow linear search for each page. One solution is to store each successful lookup in a radix tree. Signed-off-by: Chris Wilson <chris@xxxxxxxxxxxxxxxxxx> --- drivers/gpu/drm/i915/i915_drv.h | 57 ++++-------- drivers/gpu/drm/i915/i915_gem.c | 149 ++++++++++++++++++++++++++++---- drivers/gpu/drm/i915/i915_gem_stolen.c | 4 +- drivers/gpu/drm/i915/i915_gem_userptr.c | 4 +- 4 files changed, 154 insertions(+), 60 deletions(-) Am curious to know if you have any performance data to show how much of a benefit this is? Are there any real world apps that would notice or just IGT benchmarks? Reviewed-by: John Harrison <john.c.harrison@xxxxxxxxx> |
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