Dong, Eddie wrote: > Current shadow code do prefetch in FNAME(prefetch_page), but it is only > used > to choose shadow_notrap_nonpresent_pte or shadow_trap_nonpresent_pte. > > At least for L1 shadow, prefetching to get exact shadow L1 pte won't > cause > performance regression (though handling time increases slightly ) since > it > won't generate a new write protected page. > > I'm not sure that "slightly" is accurate, we need to fetch 512 or 1024 entries. On the other hand, we have the benefit of batching (a call to get_user_pages() with n = 512 is much faster than 512 calls. I think that this will improve fork()s, but reduce performance with sparsely-accessed memory maps, or with fork() followed by exec() immediately.
Only benchmarking can tell if it is an overall win. Xen limits the prefetch to a subset of the pages, maybe that's a better approach. > for those L2+ shadow page tables, we can do similar for those pointed > gfn which > is already shadowed I think L2s are very rare compared to L1 page tables, so any benefit would be minor. -- error compiling committee.c: too many arguments to function ------------------------------------------------------------------------- This SF.net email is sponsored by: Microsoft Defy all challenges. Microsoft(R) Visual Studio 2005. http://clk.atdmt.com/MRT/go/vse0120000070mrt/direct/01/ _______________________________________________ kvm-devel mailing list kvm-devel@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/kvm-devel
