On Tue, Apr 19, 2011 at 03:38:14AM +0900, Takuya Yoshikawa wrote: > From: Takuya Yoshikawa <yoshikawa.takuya@xxxxxxxxxxxxx> > > We optimize multi level guest page table walk as follows: > > 1. We cache the memslot which, probably, includes the next guest page > tables to avoid searching for it many times. > 2. We use get_user() instead of copy_from_user(). > > Note that this is kind of a restricted way of Xiao's more generic > work: "KVM: optimize memslots searching and cache GPN to GFN." > > With this patch applied, paging64_walk_addr_generic() has improved > as the following tracing results show. > > Before: > 3.169 us | paging64_walk_addr_generic(); > 1.880 us | paging64_walk_addr_generic(); > 1.243 us | paging64_walk_addr_generic(); > 1.517 us | paging64_walk_addr_generic(); > 3.009 us | paging64_walk_addr_generic(); > 1.814 us | paging64_walk_addr_generic(); > 1.340 us | paging64_walk_addr_generic(); > 1.659 us | paging64_walk_addr_generic(); > 1.748 us | paging64_walk_addr_generic(); > 1.488 us | paging64_walk_addr_generic(); > > After: > 1.714 us | paging64_walk_addr_generic(); > 0.806 us | paging64_walk_addr_generic(); > 0.664 us | paging64_walk_addr_generic(); > 0.619 us | paging64_walk_addr_generic(); > 0.645 us | paging64_walk_addr_generic(); > 0.605 us | paging64_walk_addr_generic(); > 1.388 us | paging64_walk_addr_generic(); > 0.753 us | paging64_walk_addr_generic(); > 0.594 us | paging64_walk_addr_generic(); > 0.833 us | paging64_walk_addr_generic(); Nice optimization! What scenarios have you used to test it? Joerg -- To unsubscribe from this list: send the line "unsubscribe kvm" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
