[RFC PATCH v2 5/5] docs: ABI: Add sysfs documentation interface of hardware prefetch driver

From: Kohei Tarumizu
Date: Thu Nov 04 2021 - 01:29:34 EST


This descrives the sysfs interface implemented on the hardware prefetch
driver.

Signed-off-by: Kohei Tarumizu <tarumizu.kohei@xxxxxxxxxxx>
---
.../ABI/testing/sysfs-devices-system-cpu | 58 +++++++++++++++++++
1 file changed, 58 insertions(+)

diff --git a/Documentation/ABI/testing/sysfs-devices-system-cpu b/Documentation/ABI/testing/sysfs-devices-system-cpu
index b46ef1476..caeefd320 100644
--- a/Documentation/ABI/testing/sysfs-devices-system-cpu
+++ b/Documentation/ABI/testing/sysfs-devices-system-cpu
@@ -666,3 +666,61 @@ Description: Preferred MTE tag checking mode
================ ==============================================

See also: Documentation/arm64/memory-tagging-extension.rst
+
+What: /sys/devices/system/cpu/cpu*/hwpf/l*/enable
+ /sys/devices/system/cpu/cpu*/hwpf/l*/available_dist
+ /sys/devices/system/cpu/cpu*/hwpf/l*/dist
+ /sys/devices/system/cpu/cpu*/hwpf/l*/reliable
+Date: October 2021
+Contact: Kohei Tarumizu <tarumizu.kohei@xxxxxxxxxxx>
+ Linux kernel mailing list <linux-kernel@xxxxxxxxxxxxxxx>
+Description: Parameters for the hardware prefetch driver
+
+ This sysfs interface provides Hardware Prefetch (HWPF) tunable
+ attribute files by using implementation defined registers.
+ These attribute files are corresponding to the cache level of
+ the parent directory.
+
+ enable:
+ Read/write interface to change hardware prefetch
+ enablement.
+ Read returns hardware prefetch enablement status:
+ 0: hardware prefetch is enabled
+ 1: hardware prefetch is disabled
+
+ Write '0' to enable Hardware Prefetch.
+ Write '1' to disable Hardware Prefetch.
+
+ available_dist:
+ Read only interface to get a list of values that can be
+ written to dist.
+
+ dist:
+ Read/write interface to specify the hardware prefetch
+ distance.
+ Read return the current hardware prefetch distance value
+ in bytes or the string "auto".
+
+ Write either a value in byte read from available_dist,
+ or the string "auto" to this attribuite. If you write
+ a value less than these, the value is rounded up.
+
+ The value 0 and the string "auto" are the same and have
+ a special meaning. This means that instead of setting
+ dist to a user-specified value, it operates using
+ hardware-specific values.
+
+ strong:
+ Read/write interface to change hardware prefetch
+ strongness.
+ Strong prefetch operation is surely executed, if there
+ is no corresponding data in cache.
+ Weak prefetch operation allows the hardware not to
+ execute operation depending on hardware state.
+
+ Read returns hardware prefetch strongness status:
+ 0: hardware prefetch is generated strong
+ 1: hardware prefetch is generated weak
+
+ Write '0' to hardware prefetch generate strong.
+ Write '1' to hardware prefetch generate weak.
--
2.27.0