From 25bca50e523cbe96c0207fbb92f22ff2bc28e9aa Mon Sep 17 00:00:00 2001 From: Damien Le Moal Date: Wed, 11 Aug 2021 12:36:58 +0900 Subject: [PATCH] block: improve ioprio class description comment In include/usapi/linux/ioprio.h, change the ioprio class enum comment to remove the outdated reference to CFQ and mention BFQ and mq-deadline instead. Also document the high priority NCQ command use for RT class IOs directed at ATA drives that support NCQ priority. Signed-off-by: Damien Le Moal Link: https://lore.kernel.org/r/20210811033702.368488-3-damien.lemoal@wdc.com Signed-off-by: Jens Axboe --- include/uapi/linux/ioprio.h | 10 ++++++---- 1 file changed, 6 insertions(+), 4 deletions(-) diff --git a/include/uapi/linux/ioprio.h b/include/uapi/linux/ioprio.h index 77b17e08b0da1..6b735854aebd2 100644 --- a/include/uapi/linux/ioprio.h +++ b/include/uapi/linux/ioprio.h @@ -13,10 +13,12 @@ #define IOPRIO_PRIO_VALUE(class, data) (((class) << IOPRIO_CLASS_SHIFT) | data) /* - * These are the io priority groups as implemented by CFQ. RT is the realtime - * class, it always gets premium service. BE is the best-effort scheduling - * class, the default for any process. IDLE is the idle scheduling class, it - * is only served when no one else is using the disk. + * These are the io priority groups as implemented by the BFQ and mq-deadline + * schedulers. RT is the realtime class, it always gets premium service. For + * ATA disks supporting NCQ IO priority, RT class IOs will be processed using + * high priority NCQ commands. BE is the best-effort scheduling class, the + * default for any process. IDLE is the idle scheduling class, it is only + * served when no one else is using the disk. */ enum { IOPRIO_CLASS_NONE, -- 2.30.2