From: Damien Le Moal <damien.lemoal@xxxxxxxxxxxxxxxxxx> Document ABI/testing/sysfs-block-device the sysfs attributes present under /sys/block/*/device/duration_limits for ATA and SCSI devices supporting the command duration limits feature. Signed-off-by: Damien Le Moal <damien.lemoal@xxxxxxxxxxxxxxxxxx> Signed-off-by: Niklas Cassel <niklas.cassel@xxxxxxx> --- Documentation/ABI/testing/sysfs-block-device | 150 +++++++++++++++++++ 1 file changed, 150 insertions(+) diff --git a/Documentation/ABI/testing/sysfs-block-device b/Documentation/ABI/testing/sysfs-block-device index 7ac7b19b2f72..3a32c86942f5 100644 --- a/Documentation/ABI/testing/sysfs-block-device +++ b/Documentation/ABI/testing/sysfs-block-device @@ -95,3 +95,153 @@ Description: This file does not exist if the HBA driver does not implement support for the SATA NCQ priority feature, regardless of the device support for this feature. + + +What: /sys/block/*/device/duration_limits/enable +Date: Dec, 2022 +KernelVersion: v6.3 +Contact: linux-scsi@xxxxxxxxxxxxxxx +Description: + (RW) For ATA and SCSI devices supporting the command duration + limits feature, write to the file to turn on or off the + feature. By default this feature is turned off. If the device + does not support the command duration limits feature, this + attribute does not exist (the directory + "/sys/block/\*/device/duration_limits" does not exist). + Writing "1" to this file enables the use of command duration + limits for read and write commands in the kernel and turns on + the feature on the device. Writing "0" disables the feature. + + +What: /sys/block/*/device/duration_limits/read/[1-7]/* +Date: Dec, 2022 +KernelVersion: v6.3 +Contact: linux-scsi@xxxxxxxxxxxxxxx +Description: + (RO) For ATA and SCSI devices supporting the command duration + limits feature, this shows the set of 7 command duration limits + descriptors for read commands currently set on the device. For + each of the 7 descritors, the following read-only attributes + are present: + + - duration_guideline: specifies the preferred length of time + in microseconds for the completion of a command. + + - duration_guideline_policy: specifies the policy action + taken if the duration_guideline attribute specifies a + non-zero command duration guideline that the device is + unable to achieve for a command. + + Possible values are: + + - 0x0: The device will complete the command at the + earliest possible time consistent with the specified + command duration guideline. + + - 0x1: If the specified command duration guideline has not + been achieved and the command duration guideline policy + field is not in the seventh command duration limits + descriptor, then the device continues processing that + command using the command duration limits descriptor + that has the next higher number. + + - 0x2: The device will continue processing the command as + with no command duration limits descriptor being used. + + - 0xD: The device will complete the command and an IO + failure will be reported to the user with the ETIME + error code. + + - 0xF: Same as 0xD. + + - max_active_time: specifies an upper limit in microseconds + on the time that elapses from the time at which the device + initiates actions to access, transfer, or act upon the + specified data until the time the device returns status for + the command. + + - max_active_time_policy: specifies the policy action taken + if the time used to process a command exceeds a non-zero + time specified by the max_active_time attribute. + + Possible values are: + + - 0x0: The device will complete the command at the + earliest possible time (i.e, do nothing based on the max + time limit not being met). + + - 0xD: The device will complete the command and an IO + failure will be reported to the user with the ETIME + error code. + + - 0xE: Same as 0xD. + + - 0xF: Same as 0xD. + + - max_inactive_time: specifies an upper limit in microseconds + on the time that elapses from the time at which the device + receives the command until the time at which the device + initiates actions to access, transfer, or act upon the + specified data. + + - max_inactive_time_policy: specifies the policy action taken + if a non-zero max_inactive_time limit is not met. + + Possible values are: + + - 0x0: The device will complete the command at the + earliest possible time (i.e, do nothing based on the max + time limit not being met). + + - 0xD: The device will complete the command and an IO + failure will be reported to the user with the ETIME + error code. + + - 0xF: Same as 0xD. + + +What: /sys/block/*/device/duration_limits/read/page +Date: Dec, 2022 +KernelVersion: v6.3 +Contact: linux-scsi@xxxxxxxxxxxxxxx +Description: + (RO) For ATA and SCSI devices supporting the command duration + limits feature, this shows the name of the device VPD page + specifying the set of 7 command duration limits descriptors for + read commands. Possible values are "T2A" and "T2B". + + +What: /sys/block/*/device/duration_limits/write/[1-7]/* +Date: Dec, 2022 +KernelVersion: v6.3 +Contact: linux-scsi@xxxxxxxxxxxxxxx +Description: + (RO) For ATA and SCSI devices supporting the command duration + limits feature, this shows the set of 7 command duration limits + descriptors for write commands currently set on the device. For + each of the 7 descritors, the same set of read-only attributes + as for read commands is present. + + +What: /sys/block/*/device/duration_limits/write/page +Date: Dec, 2022 +KernelVersion: v6.3 +Contact: linux-scsi@xxxxxxxxxxxxxxx +Description: + (RO) For ATA and SCSI devices supporting the command duration + limits feature, this shows the name of the device VPD page + specifying the set of 7 command duration limits descriptors for + write commands. Possible values are "T2A" and "T2B". + + +What: /sys/block/*/device/duration_limits/perf_vs_duration_guideline +Date: Dec, 2022 +KernelVersion: v6.3 +Contact: linux-scsi@xxxxxxxxxxxxxxx +Description: + (RO) For ATA and SCSI devices supporting the command duration + limits feature, this specifies the maximum percentage increase + in average command completion times (reduction in IOPS) that + is allowed for the device to perform actions based on the + contents of the duration guideline field in every command + duration limit descriptor for both read and write commands. -- 2.39.1
