For SCHED_ISO and SCHED_IDLEPRIO tasks where no ioprio is explicitly set: Set ioprio to best priority normal class for SCHED_ISO tasks. Set ioprio to idle class for SCHED_IDLEPRIO tasks. Note this means the SCHED_IDLEPRIO tasks will also get idle usage of I/O by default meaning no disk reads will be allowed when there is any I/O wait already occurring. Signed-off-by: Con Kolivas --- block/cfq-iosched.c | 2 ++ include/linux/ioprio.h | 6 ++++++ 2 files changed, 8 insertions(+) Index: linux-2.6.22-rc4-ck1/include/linux/ioprio.h =================================================================== --- linux-2.6.22-rc4-ck1.orig/include/linux/ioprio.h 2007-06-10 21:59:55.000000000 +1000 +++ linux-2.6.22-rc4-ck1/include/linux/ioprio.h 2007-06-10 21:59:55.000000000 +1000 @@ -56,6 +56,8 @@ static inline enum ioprio_class { if (rt_task(task)) return IOPRIO_CLASS_RT; + if (idleprio_task(task)) + return IOPRIO_CLASS_IDLE; return IOPRIO_CLASS_BE; } @@ -64,6 +66,10 @@ static inline int task_nice_ioprio(struc if (rt_task(task)) return (MAX_RT_PRIO - task->rt_priority) * IOPRIO_BE_NR / (MAX_RT_PRIO + 1); + if (iso_task(task)) + return 0; + if (idleprio_task(task)) + return IOPRIO_BE_NR - 1; return (task_nice(task) + 20) / 5; } Index: linux-2.6.22-rc4-ck1/block/cfq-iosched.c =================================================================== --- linux-2.6.22-rc4-ck1.orig/block/cfq-iosched.c 2007-06-10 21:59:55.000000000 +1000 +++ linux-2.6.22-rc4-ck1/block/cfq-iosched.c 2007-06-10 21:59:55.000000000 +1000 @@ -1280,6 +1280,8 @@ static void cfq_init_prio_data(struct cf */ cfqq->ioprio_class = task_policy_ioprio_class(tsk); cfqq->ioprio = task_nice_ioprio(tsk); + if (cfqq->ioprio_class == IOPRIO_CLASS_IDLE) + cfq_clear_cfqq_idle_window(cfqq); break; case IOPRIO_CLASS_RT: cfqq->ioprio = task_ioprio(tsk);