Re: [PATCH v11 06/10] fs/resctrl: Add user interface to enable/disable io_alloc feature

From: Babu Moger

Date: Mon Nov 03 2025 - 16:36:29 EST


Hi Reinette,

On 11/3/25 13:05, Reinette Chatre wrote:
Hi Babu,

On 10/30/25 10:15 AM, Babu Moger wrote:

...

diff --git a/Documentation/filesystems/resctrl.rst b/Documentation/filesystems/resctrl.rst
index 108995640ca5..89e856e6892c 100644
--- a/Documentation/filesystems/resctrl.rst
+++ b/Documentation/filesystems/resctrl.rst
@@ -152,6 +152,29 @@ related to allocation:
"not supported":
Support not available for this resource.
+ The feature can be modified by writing to the interface, for example:
+
+ To enable:
+ # echo 1 > /sys/fs/resctrl/info/L3/io_alloc
+
+ To disable:
+ # echo 0 > /sys/fs/resctrl/info/L3/io_alloc
+
Above examples are missing the '::' that will format them as fixed width text blocks
used for these shell examples.

Sure. Will update:

diff --git a/Documentation/filesystems/resctrl.rst b/Documentation/filesystems/resctrl.rst
index ccc425b65b27..cd2214d8026e 100644
--- a/Documentation/filesystems/resctrl.rst
+++ b/Documentation/filesystems/resctrl.rst
@@ -161,10 +161,12 @@ related to allocation:

                The feature can be modified by writing to the interface, for example:

-               To enable:
+               To enable::
+
                        # echo 1 > /sys/fs/resctrl/info/L3/io_alloc

-               To disable:
+               To disable::
+
                        # echo 0 > /sys/fs/resctrl/info/L3/io_alloc

                The underlying implementation may reduce resources available to


+ The underlying implementation may reduce resources available to
+ general (CPU) cache allocation. See architecture specific notes
+ below. Depending on usage requirements the feature can be enabled
+ or disabled.
+
+ On AMD systems, io_alloc feature is supported by the L3 Smart
+ Data Cache Injection Allocation Enforcement (SDCIAE). The CLOSID for
+ io_alloc is the highest CLOSID supported by the resource. When
+ io_alloc is enabled, the highest CLOSID is dedicated to io_alloc and
+ no longer available for general (CPU) cache allocation. When CDP is
+ enabled, io_alloc routes I/O traffic using the highest CLOSID allocated
+ for the instruction cache (CDP_CODE), making this CLOSID no longer
+ available for general (CPU) cache allocation for both the CDP_CODE
+ and CDP_DATA resources.
+
Memory bandwidth(MB) subdirectory contains the following files
with respect to allocation:
With the doc formatting fixed:
| Reviewed-by: Reinette Chatre <reinette.chatre@xxxxxxxxx>


Thank you.

Babu