2014-08-20 15:15+0200, Paolo Bonzini: > Il 20/08/2014 14:41, Radim Krčmář ha scritto: > >> > if (ple_window_grow < 1 || ple_window_actual_max < ple_window) > >> > new = ple_window; > >> > else if (ple_window_grow < ple_window) > >> > new = max(ple_window_actual_max, old) * ple_window_grow; > >> > else > >> > new = max(ple_window_actual_max, old) + ple_window_grow; > > Oh, I like that this can get rid of all overflows, ple_window_actual_max > > (PW_effective_max?) is going to be set to > > "ple_window_max [/-] ple_window_grow" in v2. > > > >> > (I think the || in the first "if" can be eliminated with some creativity > >> > in clamp_ple_window_max). > > To do it, we'll want to intercept changes to ple_window as well. > > (I disliked this patch a lot even before :) > > What about setting ple_window_actual_max to 0 if ple_window_grow is 0 > (instead of just returning)? > > Then the "if (ple_window_actual_max < ple_window)" will always fail and > you'll go through "new = ple_window". But perhaps it's more gross and > worthless than creative. :) That code can't use PW directly, because PW_actual_max needs to be one PW_grow below PW_max, so I'd rather enforce minimal PW_actual_max. Btw. without extra code, we are still going to overflow on races when changing PW_grow, should they be covered as well? (+ There is a bug in this patch -- clamp_ple_window_max() should be after param_set_int() ... damned unreviewed last-second changes.) -- 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
