On Wed, May 07, 2008 at 06:02:49PM -0700, Linus Torvalds wrote: > You replace mm_lock() with the sequence that Andrew gave you (and I > described): > > spin_lock(&global_lock) > .. get all locks UNORDERED .. > spin_unlock(&global_lock) > > and you're now done. You have your "mm_lock()" (which still needs to be > renamed - it should be a "mmu_notifier_lock()" or something like that), > but you don't need the insane sorting. At most you apparently need a way > to recognize duplicates (so that you don't deadlock on yourself), which > looks like a simple bit-per-vma. > > The global lock doesn't protect any data structures itself - it just > protects two of these mm_lock() functions from ABBA'ing on each other!
I thought the thing to remove was the "get all locks". I didn't realize the major problem was only the sorting of the array. I'll add the global lock, it's worth it as it drops the worst case number of steps by log(65536) times. Furthermore surely two concurrent mm_notifier_lock will run faster as it'll decrease the cacheline collisions. Since you ask to call it mmu_notifier_lock I'll also move it to mmu_notifier.[ch] as consequence. ------------------------------------------------------------------------- This SF.net email is sponsored by the 2008 JavaOne(SM) Conference Don't miss this year's exciting event. There's still time to save $100. Use priority code J8TL2D2. http://ad.doubleclick.net/clk;198757673;13503038;p?http://java.sun.com/javaone _______________________________________________ kvm-devel mailing list kvm-devel@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/kvm-devel
