On Tue, 20 Nov 2012, Ingo Molnar wrote: > Subject: x86/mm: Don't flush the TLB on #WP pmd fixups > From: Ingo Molnar <mingo@xxxxxxxxxx> > 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%) -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@xxxxxxxxx. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: <a href=mailto:"dont@xxxxxxxxx";> email@xxxxxxxxx </a>