Messages in this thread | | | Date | Wed, 22 May 2002 12:19:29 +0100 | From | Russell King <> | Subject | Re: Linux-2.5.17 |
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On Mon, May 20, 2002 at 10:16:35PM -0700, Linus Torvalds wrote: > Various FS updates (including merges of quota and iget_locked), and > Makefile cleanups from Kai. > > And yet more TLB shootdown stuff.
We seem to have inconsistent cache handling in the new TLB shootdown stuff. Or maybe its just my misunderstanding of what's going on; whatever it is, the new TLB shootdown stuff appears to be quite messy.
Lets look at the flow of the 3 places where tlb_gather_mmu is used:
zap_page_range unmap_region exit_mmap flush_cache_range tlb_gather_mmu tlb_gather_mmu tlb_gather_mmu unmap_page_range flush_cache_mm unmap_page_range free_pgtables unmap_page_range tlb_finish_mmu tlb_finish_mmu clear_page_tables tlb_finish_mmu
So we have 3 different functions, 2 different orders of gather_mmu and cache handling, and one with no cache handling what so ever.
I think we have two options - either leave the cache handling up to tlb_start_vma() (in which case, flush_cache_range and flush_cache_mm are redundant and should be removed) or let it be up to the caller of tlb_gather_mmu to call the right cache handling function.
I think which is actually function dependent - in zap_page_range, we're only removing one vma. In exit_mmap, we're removing all vmas. In unmap_region, we're removing an unspecified number of vmas. Depending on which option we choose, we'll either end up calling flush_cache_range() many times, or flush_cache_mm() and flushing the cache for a munmap of a small area.
-- Russell King (rmk@arm.linux.org.uk) The developer of ARM Linux http://www.arm.linux.org.uk/personal/aboutme.html
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