A minor fix to this patch. While testing the fio mmap workload, bdi->dirty_ratelimit is observed to be knocked down to 1 and then brought up high in regular intervals. The showed up problem is, it took long delays to bring up bdi->dirty_ratelimit due to the round-down problem of the below task_ratelimit calculation: when dirty_ratelimit=1 and pos_ratio = 1.5, the resulted task_ratelimit will be 1, which fooled stops the logic from increasing dirty_ratelimit as long as pos_ratio < 2. The below change (from round-down to round-up) can nicely fix this problem. Thanks, Fengguang --- --- linux-next.orig/mm/page-writeback.c 2011-09-24 15:52:11.000000000 +0800 +++ linux-next/mm/page-writeback.c 2011-09-24 15:52:11.000000000 +0800 @@ -766,6 +766,7 @@ static void bdi_update_dirty_ratelimit(s */ task_ratelimit = (u64)dirty_ratelimit * pos_ratio >> RATELIMIT_CALC_SHIFT; + task_ratelimit++; /* it helps rampup dirty_ratelimit from tiny values */ /* * A linear estimation of the "balanced" throttle rate. The theory is, -- To unsubscribe from this list: send the line "unsubscribe linux-fsdevel" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
