Messages in this thread | | | Date | Thu, 28 Feb 2008 17:17:33 -0600 | From | Jack Steiner <> | Subject | Re: [PATCH] mmu notifiers #v7 |
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> > The release should be called much earlier to allow the driver to release > > all resources in one go. This way each vma must be processed individually. > > For our gobs of memory this method may create a scaling problem on exit(). > > Good point, it has to be called earlier for GRU, but it's not a > performance issue. GRU doesn't pin the pages so it should make the > global invalidate in ->release _before_ unmap_vmas. Linux can't fault > in the ptes anymore because mm_users is zero so there's no need of a > ->release_begin/end, the _begin is enough. >
I disagree. The location of the callout IS a performance issue. In simple comparisons of the 2 patches (Christoph's vs. Andrea's), Andrea's has a 7X increase in the number of TLB purges being issued to the GRU. TLB flushing is slow and can impact the performance of of tasks using the GRU.
--- jack
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