When the io_alloc feature is enabled, a portion of the cache can be
configured for shared use between hardware and software.
Update bit_usage representation to reflect the io_alloc configuration.
Revise the documentation for "shareable_bits" and "bit_usage" to reflect
the impact of io_alloc feature.
Signed-off-by: Babu Moger <babu.moger@amd.com>
---
v9: Changelog update.
Added code comments about CDP.
Updated the "bit_usage" section of resctrl.rst for io_alloc.
v8: Moved the patch to last after all the concepts are initialized.
Updated user doc resctrl.rst.
Simplified the CDT check in rdt_bit_usage_show() as CDP_DATA and CDP_CODE
are in sync with io_alloc enabled.
v7: New patch split from earlier patch #5.
Added resctrl_io_alloc_closid() to return max COSID.
---
Documentation/filesystems/resctrl.rst | 35 ++++++++++++++++-----------
fs/resctrl/ctrlmondata.c | 2 +-
fs/resctrl/internal.h | 2 ++
fs/resctrl/rdtgroup.c | 21 ++++++++++++++--
4 files changed, 43 insertions(+), 17 deletions(-)
diff --git a/Documentation/filesystems/resctrl.rst b/Documentation/filesystems/resctrl.rst
index 7e3eda324de5..72ea6f3f36bc 100644
--- a/Documentation/filesystems/resctrl.rst
+++ b/Documentation/filesystems/resctrl.rst
@@ -90,12 +90,19 @@ related to allocation:
must be set when writing a mask.
"shareable_bits":
- Bitmask of shareable resource with other executing
- entities (e.g. I/O). User can use this when
- setting up exclusive cache partitions. Note that
- some platforms support devices that have their
- own settings for cache use which can over-ride
- these bits.
+ Bitmask of shareable resource with other executing entities
+ (e.g. I/O). Applies to all instances of this resource. User
+ can use this when setting up exclusive cache partitions.
+ Note that some platforms support devices that have their
+ own settings for cache use which can over-ride these bits.
+
+ When "io_alloc" is enabled, a portion of each cache instance can
+ be configured for shared use between hardware and software.
+ "bit_usage" should be used to see which portions of each cache
+ instance is configured for hardware use via "io_alloc" feature
+ because every cache instance can have its "io_alloc" bitmask
+ configured independently via io_alloc_cbm.
+
"bit_usage":
Annotated capacity bitmasks showing how all
instances of the resource are used. The legend is:
@@ -109,16 +116,16 @@ related to allocation:
"H":
Corresponding region is used by hardware only
but available for software use. If a resource
- has bits set in "shareable_bits" but not all
- of these bits appear in the resource groups'
- schematas then the bits appearing in
- "shareable_bits" but no resource group will
- be marked as "H".
+ has bits set in "shareable_bits" or "io_alloc_cbm"
+ but not all of these bits appear in the resource
+ groups' schematas then the bits appearing in
+ "shareable_bits" or "io_alloc_cbm" but no
+ resource group will be marked as "H".
"X":
Corresponding region is available for sharing and
- used by hardware and software. These are the
- bits that appear in "shareable_bits" as
- well as a resource group's allocation.
+ used by hardware and software. These are the bits
+ that appear in "shareable_bits" or "io_alloc_cbm"
+ as well as a resource group's allocation.
"S":
Corresponding region is used by software
and available for sharing.
diff --git a/fs/resctrl/ctrlmondata.c b/fs/resctrl/ctrlmondata.c
index 791ecb559b50..1118054fdc2c 100644
--- a/fs/resctrl/ctrlmondata.c
+++ b/fs/resctrl/ctrlmondata.c
@@ -738,7 +738,7 @@ static int resctrl_io_alloc_init_cbm(struct resctrl_schema *s, u32 closid)
* resource. Note that if Code Data Prioritization (CDP) is enabled, the number
* of available CLOSIDs is reduced by half.
*/
-static u32 resctrl_io_alloc_closid(struct rdt_resource *r)
+u32 resctrl_io_alloc_closid(struct rdt_resource *r)
{
if (resctrl_arch_get_cdp_enabled(r->rid))
return resctrl_arch_get_num_closid(r) / 2 - 1;
diff --git a/fs/resctrl/internal.h b/fs/resctrl/internal.h
index 5467c3ad1b6d..98b87725508b 100644
--- a/fs/resctrl/internal.h
+++ b/fs/resctrl/internal.h
@@ -395,6 +395,8 @@ int resctrl_io_alloc_cbm_show(struct kernfs_open_file *of, struct seq_file *seq,
ssize_t resctrl_io_alloc_cbm_write(struct kernfs_open_file *of, char *buf,
size_t nbytes, loff_t off);
+u32 resctrl_io_alloc_closid(struct rdt_resource *r);
+
const char *rdtgroup_name_by_closid(int closid);
#ifdef CONFIG_RESCTRL_FS_PSEUDO_LOCK
diff --git a/fs/resctrl/rdtgroup.c b/fs/resctrl/rdtgroup.c
index ddac021c02d8..951d44d6f488 100644
--- a/fs/resctrl/rdtgroup.c
+++ b/fs/resctrl/rdtgroup.c
@@ -1068,15 +1068,17 @@ static int rdt_bit_usage_show(struct kernfs_open_file *of,
cpus_read_lock();
mutex_lock(&rdtgroup_mutex);
- hw_shareable = r->cache.shareable_bits;
list_for_each_entry(dom, &r->ctrl_domains, hdr.list) {
if (sep)
seq_putc(seq, ';');
+ hw_shareable = r->cache.shareable_bits;
sw_shareable = 0;
exclusive = 0;
seq_printf(seq, "%d=", dom->hdr.id);
for (i = 0; i < closids_supported(); i++) {
- if (!closid_allocated(i))
+ if (!closid_allocated(i) ||
+ (resctrl_arch_get_io_alloc_enabled(r) &&
+ i == resctrl_io_alloc_closid(r)))
continue;
ctrl_val = resctrl_arch_get_config(r, dom, i,
s->conf_type);
@@ -1104,6 +1106,21 @@ static int rdt_bit_usage_show(struct kernfs_open_file *of,
break;
}
}
+
+ /*
+ * When the "io_alloc" feature is enabled, a portion of the cache
+ * is configured for shared use between hardware and software.
+ * Also, when CDP is enabled the CBMs of L3CODE and L3DATA are kept
+ * in sync. So, the CBMs for "io_alloc" can be accessed through either
+ * L3CODE or L3DATA.
+ */
+ if (resctrl_arch_get_io_alloc_enabled(r)) {
+ ctrl_val = resctrl_arch_get_config(r, dom,
+ resctrl_io_alloc_closid(r),
+ s->conf_type);
+ hw_shareable |= ctrl_val;
+ }
+
for (i = r->cache.cbm_len - 1; i >= 0; i--) {
pseudo_locked = dom->plr ? dom->plr->cbm : 0;
hwb = test_bit(i, &hw_shareable);
--
2.34.1Hi Babu,
On 9/2/25 3:41 PM, Babu Moger wrote:
> When the io_alloc feature is enabled, a portion of the cache can be
> configured for shared use between hardware and software.
(repetitive)
>
> Update bit_usage representation to reflect the io_alloc configuration.
> Revise the documentation for "shareable_bits" and "bit_usage" to reflect
> the impact of io_alloc feature.
Attempt at new version, please feel free to improve:
The "shareable_bits" and "bit_usage" resctrl files associated with cache
resources give insight into how instances of a cache is used.
Update the annotated capacity bitmasks displayed by "bit_usage" to include the
cache portions allocated for I/O via the "io_alloc" feature. "shareable_bits" is
a global bitmask of shareable cache with I/O and can thus not present the
per-domain I/O allocations possible with the "io_alloc" feature. Revise the
"shareable_bits" documentation to direct users to "bit_usage" for accurate
cache usage information.
>
> Signed-off-by: Babu Moger <babu.moger@amd.com>
> ---
...
> ---
> Documentation/filesystems/resctrl.rst | 35 ++++++++++++++++-----------
> fs/resctrl/ctrlmondata.c | 2 +-
> fs/resctrl/internal.h | 2 ++
> fs/resctrl/rdtgroup.c | 21 ++++++++++++++--
> 4 files changed, 43 insertions(+), 17 deletions(-)
>
> diff --git a/Documentation/filesystems/resctrl.rst b/Documentation/filesystems/resctrl.rst
> index 7e3eda324de5..72ea6f3f36bc 100644
> --- a/Documentation/filesystems/resctrl.rst
> +++ b/Documentation/filesystems/resctrl.rst
> @@ -90,12 +90,19 @@ related to allocation:
> must be set when writing a mask.
>
> "shareable_bits":
> - Bitmask of shareable resource with other executing
> - entities (e.g. I/O). User can use this when
> - setting up exclusive cache partitions. Note that
> - some platforms support devices that have their
> - own settings for cache use which can over-ride
> - these bits.
> + Bitmask of shareable resource with other executing entities
> + (e.g. I/O). Applies to all instances of this resource. User
> + can use this when setting up exclusive cache partitions.
> + Note that some platforms support devices that have their
> + own settings for cache use which can over-ride these bits.
> +
> + When "io_alloc" is enabled, a portion of each cache instance can
> + be configured for shared use between hardware and software.
> + "bit_usage" should be used to see which portions of each cache
> + instance is configured for hardware use via "io_alloc" feature
> + because every cache instance can have its "io_alloc" bitmask
> + configured independently via io_alloc_cbm.
io_alloc_cbm -> "io_alloc_cbm" (to consistently place names of resctrl files in quotes)
> +
> "bit_usage":
> Annotated capacity bitmasks showing how all
> instances of the resource are used. The legend is:
> @@ -109,16 +116,16 @@ related to allocation:
> "H":
> Corresponding region is used by hardware only
> but available for software use. If a resource
> - has bits set in "shareable_bits" but not all
> - of these bits appear in the resource groups'
> - schematas then the bits appearing in
> - "shareable_bits" but no resource group will
> - be marked as "H".
> + has bits set in "shareable_bits" or "io_alloc_cbm"
> + but not all of these bits appear in the resource
> + groups' schematas then the bits appearing in
I understand that you are just copying this but "schemata" is plural of "schema". Since you
are copying this text, could you please fix "schematas" to be "schemata" while doing so?
> + "shareable_bits" or "io_alloc_cbm" but no
> + resource group will be marked as "H".
> "X":
> Corresponding region is available for sharing and
> - used by hardware and software. These are the
> - bits that appear in "shareable_bits" as
> - well as a resource group's allocation.
> + used by hardware and software. These are the bits
> + that appear in "shareable_bits" or "io_alloc_cbm"
> + as well as a resource group's allocation.
> "S":
> Corresponding region is used by software
> and available for sharing.
Reinette
Hi Reinette, On 9/18/2025 1:08 AM, Reinette Chatre wrote: > Hi Babu, > > On 9/2/25 3:41 PM, Babu Moger wrote: >> When the io_alloc feature is enabled, a portion of the cache can be >> configured for shared use between hardware and software. > > (repetitive) > >> >> Update bit_usage representation to reflect the io_alloc configuration. >> Revise the documentation for "shareable_bits" and "bit_usage" to reflect >> the impact of io_alloc feature. > > Attempt at new version, please feel free to improve: > > The "shareable_bits" and "bit_usage" resctrl files associated with cache > resources give insight into how instances of a cache is used. > > Update the annotated capacity bitmasks displayed by "bit_usage" to include the > cache portions allocated for I/O via the "io_alloc" feature. "shareable_bits" is > a global bitmask of shareable cache with I/O and can thus not present the > per-domain I/O allocations possible with the "io_alloc" feature. Revise the > "shareable_bits" documentation to direct users to "bit_usage" for accurate > cache usage information. > Looks good. Thanks >> >> Signed-off-by: Babu Moger <babu.moger@amd.com> >> --- > > ... > >> --- >> Documentation/filesystems/resctrl.rst | 35 ++++++++++++++++----------- >> fs/resctrl/ctrlmondata.c | 2 +- >> fs/resctrl/internal.h | 2 ++ >> fs/resctrl/rdtgroup.c | 21 ++++++++++++++-- >> 4 files changed, 43 insertions(+), 17 deletions(-) >> >> diff --git a/Documentation/filesystems/resctrl.rst b/Documentation/filesystems/resctrl.rst >> index 7e3eda324de5..72ea6f3f36bc 100644 >> --- a/Documentation/filesystems/resctrl.rst >> +++ b/Documentation/filesystems/resctrl.rst >> @@ -90,12 +90,19 @@ related to allocation: >> must be set when writing a mask. >> >> "shareable_bits": >> - Bitmask of shareable resource with other executing >> - entities (e.g. I/O). User can use this when >> - setting up exclusive cache partitions. Note that >> - some platforms support devices that have their >> - own settings for cache use which can over-ride >> - these bits. >> + Bitmask of shareable resource with other executing entities >> + (e.g. I/O). Applies to all instances of this resource. User >> + can use this when setting up exclusive cache partitions. >> + Note that some platforms support devices that have their >> + own settings for cache use which can over-ride these bits. >> + >> + When "io_alloc" is enabled, a portion of each cache instance can >> + be configured for shared use between hardware and software. >> + "bit_usage" should be used to see which portions of each cache >> + instance is configured for hardware use via "io_alloc" feature >> + because every cache instance can have its "io_alloc" bitmask >> + configured independently via io_alloc_cbm. > > io_alloc_cbm -> "io_alloc_cbm" (to consistently place names of resctrl files in quotes) Sure. > >> + >> "bit_usage": >> Annotated capacity bitmasks showing how all >> instances of the resource are used. The legend is: >> @@ -109,16 +116,16 @@ related to allocation: >> "H": >> Corresponding region is used by hardware only >> but available for software use. If a resource >> - has bits set in "shareable_bits" but not all >> - of these bits appear in the resource groups' >> - schematas then the bits appearing in >> - "shareable_bits" but no resource group will >> - be marked as "H". >> + has bits set in "shareable_bits" or "io_alloc_cbm" >> + but not all of these bits appear in the resource >> + groups' schematas then the bits appearing in > > I understand that you are just copying this but "schemata" is plural of "schema". Since you > are copying this text, could you please fix "schematas" to be "schemata" while doing so? Sure. Thanks Babu
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