On Friday 25 January 2008 06:21, Jeremy Fitzhardinge wrote: > Matt Mackall wrote: > > There's perhaps an opportunity to do this lazy TLB trick in the mmap > > path as well, where RW mappings are initially mapped as RO so we can > > catch processes dirtying them and then switched to RW. If the mapping is > > shared across threads on multiple cores, we can defer synchronizing the > > TLBs on the others. > > I think spurious usermode faults are already dealt with. > handle_pte_fault() does essentially the same thing as this patch: > > if (ptep_set_access_flags(vma, address, pte, entry, write_access)) { > update_mmu_cache(vma, address, entry); > } else { > /* > * This is needed only for protection faults but the arch code > * is not yet telling us if this is a protection fault or not. > * This still avoids useless tlb flushes for .text page faults > * with threads. > */ > if (write_access) > flush_tlb_page(vma, address); > }
I (obviously) don't know exactly how the TLB works in x86, but I thought that on a miss, the CPU walks the pagetables first before faulting? Maybe that's not the case if there is an RO entry actually in the TLB? -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [EMAIL PROTECTED] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/