Debug patch only. This implements CFQ like sync preempts async. But like CFQ, this will starve async. --- block/fiops-iosched.c | 15 +++++++++++++++ 1 file changed, 15 insertions(+) Index: linux/block/fiops-iosched.c =================================================================== --- linux.orig/block/fiops-iosched.c 2012-01-21 10:35:04.000000000 +0800 +++ linux/block/fiops-iosched.c 2012-01-21 10:48:52.000000000 +0800 @@ -408,6 +408,21 @@ static struct fiops_ioc *fiops_select_io return NULL; } + /* Let sync request preempt async queue */ + if (!rq_is_sync(rq) && service_tree->count > 1) { + struct rb_node *tmp = rb_next(&ioc->rb_node); + struct fiops_ioc *sync_ioc = NULL; + while (tmp) { + sync_ioc = rb_entry(tmp, struct fiops_ioc, rb_node); + rq = rq_entry_fifo(sync_ioc->fifo.next); + if (rq_is_sync(rq)) + break; + tmp = rb_next(&sync_ioc->rb_node); + } + if (sync_ioc) + ioc = sync_ioc; + } + return ioc; } -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/