Re: [PATCH 7/8] mm: thp: Use more portable PMD clearing sequenece in zap_huge_pmd().
On Tue, Oct 02, 2012 at 06:27:41PM -0400, David Miller wrote: > > Invalidation sequences are handled in various ways on various > architectures. > > One way, which sparc64 uses, is to let the set_*_at() functions > accumulate pending flushes into a per-cpu array. Then the > flush_tlb_range() et al. calls process the pending TLB flushes. > > In this regime, the __tlb_remove_*tlb_entry() implementations are > essentially NOPs. > > The canonical PTE zap in mm/memory.c is: > > ptent = ptep_get_and_clear_full(mm, addr, pte, > tlb->fullmm); > tlb_remove_tlb_entry(tlb, pte, addr); > > With a subsequent tlb_flush_mmu() if needed. > > Mirror this in the THP PMD zapping using: > > orig_pmd = pmdp_get_and_clear(tlb->mm, addr, pmd); > page = pmd_page(orig_pmd); > tlb_remove_pmd_tlb_entry(tlb, pmd, addr); > > And we properly accomodate TLB flush mechanims like the one described > above. Thanks for the explanation. Reviewed-by: Andrea Arcangeli -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
Re: [PATCH 7/8] mm: thp: Use more portable PMD clearing sequenece in zap_huge_pmd().
On Tue, Oct 02, 2012 at 06:27:41PM -0400, David Miller wrote: Invalidation sequences are handled in various ways on various architectures. One way, which sparc64 uses, is to let the set_*_at() functions accumulate pending flushes into a per-cpu array. Then the flush_tlb_range() et al. calls process the pending TLB flushes. In this regime, the __tlb_remove_*tlb_entry() implementations are essentially NOPs. The canonical PTE zap in mm/memory.c is: ptent = ptep_get_and_clear_full(mm, addr, pte, tlb-fullmm); tlb_remove_tlb_entry(tlb, pte, addr); With a subsequent tlb_flush_mmu() if needed. Mirror this in the THP PMD zapping using: orig_pmd = pmdp_get_and_clear(tlb-mm, addr, pmd); page = pmd_page(orig_pmd); tlb_remove_pmd_tlb_entry(tlb, pmd, addr); And we properly accomodate TLB flush mechanims like the one described above. Thanks for the explanation. Reviewed-by: Andrea Arcangeli aarca...@redhat.com -- To unsubscribe from this list: send the line unsubscribe linux-kernel in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
