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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In include/usapi/linux/ioprio.h, change the ioprio class enum comment to remove the outdated reference to CFQ and mention BFQ and mq-deadline instead.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.

Damien Le Moal committed 5 years ago

Commit 25bca501 parent a680dd71 file · +6 −4Browse files

Unified · Split

include/uapi/linux/ioprio.h+6−4
@@ -13,10 +13,12 @@ · 12 unmodified lines
13#define IOPRIO_PRIO_VALUE(class, data) (((class) << IOPRIO_CLASS_SHIFT) | data)13#define IOPRIO_PRIO_VALUE(class, data) (((class) << IOPRIO_CLASS_SHIFT) | data)
14 14
15/*15/*
16 * These are the io priority groups as implemented by CFQ. RT is the realtime16 * These are the io priority groups as implemented by the BFQ and mq-deadline
17 * class, it always gets premium service. BE is the best-effort scheduling17 * schedulers. RT is the realtime class, it always gets premium service. For
18 * class, the default for any process. IDLE is the idle scheduling class, it18 * ATA disks supporting NCQ IO priority, RT class IOs will be processed using
19 * is only served when no one else is using the disk.19 * high priority NCQ commands. BE is the best-effort scheduling class, the
20 * default for any process. IDLE is the idle scheduling class, it is only
21 * served when no one else is using the disk.
20 */22 */
21enum {23enum {
22 IOPRIO_CLASS_NONE,24 IOPRIO_CLASS_NONE,