• Rusty Russell's avatar
    lguest: restore boot speed · bb4093de
    Rusty Russell authored
    
    
    lguest is dumb and drops *all* the pagetables for set_pte (which is
    only used for kernel mapping manipulation, so it's OK without highmem).
    
    But it's used a lot in boot, too.  As a guest optimization, we
    suppressed this flushing until the first page switch.  Now we have
    initial_page_table, that happens much earlier, so extend the heuristic
    to wait until we switch to something other than the swapper_pg_dir or
    initial_page_table.
    
    As measured on my laptop under kvm, this dropped the time-to-mount-root
    from 48 seconds to 4.3 seconds.
    Signed-off-by: default avatarRusty Russell <rusty@rustcorp.com.au>
    bb4093de
boot.c 47.5 KB