On Thu, 22 Aug 2024 21:58:02 -0500
Ira Weiny [off-list ref] wrote:

Dave Jiang wrote:

quoted

On 8/16/24 7:44 AM, ira.weiny@intel.com wrote:  

quoted

From: Navneet Singh <redacted>

Extent information can be helpful to the user to coordinate memory usage
with the external orchestrator and FM.

Expose the details of region extents by creating the following
sysfs entries.

        /sys/bus/cxl/devices/dax_regionX/extentX.Y
        /sys/bus/cxl/devices/dax_regionX/extentX.Y/offset
        /sys/bus/cxl/devices/dax_regionX/extentX.Y/length
        /sys/bus/cxl/devices/dax_regionX/extentX.Y/tag

Signed-off-by: Navneet Singh <redacted>
Co-developed-by: Ira Weiny <redacted>
Signed-off-by: Ira Weiny <redacted>

---
Changes:
[iweiny: split this out]
[Jonathan: add documentation for extent sysfs]
[Jonathan/djbw: s/label/tag]
[Jonathan/djbw: treat tag as uuid]
[djbw: use __ATTRIBUTE_GROUPS]
[djbw: make tag invisible if it is empty]
[djbw/iweiny: use conventional id names for extents; extentX.Y]
---
 Documentation/ABI/testing/sysfs-bus-cxl | 13 ++++++++
 drivers/cxl/core/extent.c               | 58 +++++++++++++++++++++++++++++++++
 2 files changed, 71 insertions(+)

diff --git a/Documentation/ABI/testing/sysfs-bus-cxl b/Documentation/ABI/testing/sysfs-bus-cxl
index 3a5ee88e551b..e97e6a73c960 100644
--- a/Documentation/ABI/testing/sysfs-bus-cxl
+++ b/Documentation/ABI/testing/sysfs-bus-cxl

@@ -599,3 +599,16 @@ Description:
 		See Documentation/ABI/stable/sysfs-devices-node. access0 provides
 		the number to the closest initiator and access1 provides the
 		number to the closest CPU.
+
+What:		/sys/bus/cxl/devices/dax_regionX/extentX.Y/offset
+		/sys/bus/cxl/devices/dax_regionX/extentX.Y/length
+		/sys/bus/cxl/devices/dax_regionX/extentX.Y/tag  

I wonder consider an entry for each with their own descriptions, which seems to be the standard practice.  

:-/  Except kind of for the access'.

What:           /sys/bus/cxl/devices/regionZ/accessY/read_bandwidth
                /sys/bus/cxl/devices/regionZ/accessY/write_banwidth

What:           /sys/bus/cxl/devices/regionZ/accessY/read_latency
                /sys/bus/cxl/devices/regionZ/accessY/write_latency

But I think you have a point.

It's a balance between complexity and repetition.

E.g. https://elixir.bootlin.com/linux/v6.11-rc4/source/Documentation/ABI/testing/sysfs-bus-iio#L427
is one of these files I know far too well. That would be a lot
of very boring repetition and that doc is long enough without breaking them up.

Here there are only 3 and a good bit of description differs so
probably good to split up.

Less so for bandwidth and latency cases.

Jonathan

Ira

quoted

DJ
  

[snip]