Messages in this thread | | | Date | Tue, 20 Nov 2012 17:22:05 -0800 (PST) | From | David Rientjes <> | Subject | Re: [PATCH] x86/mm: Don't flush the TLB on #WP pmd fixups |
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On Tue, 20 Nov 2012, Ingo Molnar wrote:
> Subject: x86/mm: Don't flush the TLB on #WP pmd fixups > From: Ingo Molnar <mingo@kernel.org> > Date: Tue Nov 20 14:46:34 CET 2012 > > If we have a write protection #PF and fix up the pmd then the > hugetlb code [the only user of pmdp_set_access_flags], in its > do_huge_pmd_wp_page() page fault resolution function calls > pmdp_set_access_flags() to mark the pmd permissive again, > and flushes the TLB. > > This TLB flush is unnecessary: a flush on #PF is guaranteed on > most (all?) x86 CPUs, and even in the worst-case we'll generate > a spurious fault. > > So remove it. >
This patch did not cause the 2% speedup that you reported with THP enabled for me:
numa/core at ec05a2311c35: 136918.34 SPECjbb2005 bops numa/core at 01aa90068b12: 128315.19 SPECjbb2005 bops (-6.3%) numa/core at 01aa90068b12 + patch: 128184.77 SPECjbb2005 bops (-6.4%)
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