"io_alloc" feature in resctrl allows direct insertion of data from I/O
devices into the cache.
Introduce the 'io_alloc' resctrl file to indicate the support for the
feature.
Signed-off-by: Babu Moger <babu.moger@xxxxxxx>
---
v7: Updated the changelog.
Updated user doc for io_alloc in resctrl.rst.
Added mutex rdtgroup_mutex in resctrl_io_alloc_show();
v6: Added "io_alloc_cbm" details in user doc resctrl.rst.
Resource name is not printed in CBM now. Corrected the texts about it
in resctrl.rst.
v5: Resolved conflicts due to recent resctrl FS/ARCH code restructure.
Updated show_doms() to print the resource if only it is valid. Pass NULL while
printing io_alloc CBM.
Changed the code to access the CBMs via either L3CODE or L3DATA resources.
v4: Updated the change log.
Added rdtgroup_mutex before rdt_last_cmd_puts().
Returned -ENODEV when resource type is CDP_DATA.
Kept the resource name while printing the CBM (L3:0=fff) that way
I dont have to change show_doms() just for this feature and it is
consistant across all the schemata display.
v3: Minor changes due to changes in resctrl_arch_get_io_alloc_enabled()
and resctrl_io_alloc_closid_get().
Added the check to verify CDP resource type.
Updated the commit log.
v2: Fixed to display only on L3 resources.
Added the locks while processing.
Rename the displat to io_alloc_cbm (from sdciae_cmd).
---
Documentation/filesystems/resctrl.rst | 25 +++++++++++++++++
fs/resctrl/rdtgroup.c | 39 +++++++++++++++++++++++++++
2 files changed, 64 insertions(+)
diff --git a/Documentation/filesystems/resctrl.rst b/Documentation/filesystems/resctrl.rst
index c3c412733632..354e6a00fa45 100644
--- a/Documentation/filesystems/resctrl.rst
+++ b/Documentation/filesystems/resctrl.rst
@@ -143,6 +143,31 @@ related to allocation:
"1":
Non-contiguous 1s value in CBM is supported.
+"io_alloc":
+ "io_alloc" enables system software to configure the portion of
+ the cache allocated for I/O traffic. File may only exist if the
+ system supports this feature on some of its cache resources.
+
+ "disabled":
+ Portions of cache used for allocation of I/O traffic
+ cannot be configured.
+ "enabled":
+ Portions of cache used for allocation of I/O traffic
+ can be configured using "io_alloc_cbm".
+ "not supported":
+ Support not available on the system.
+
+ 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, the io_alloc feature is supported by the L3 Smart
+ Data Cache Injection Allocation Enforcement (SDCIAE). The CLOSID for
+ io_alloc is determined by the highest CLOSID supported by the resource.
+ When CDP is enabled, io_alloc routes I/O traffic using the highest
+ CLOSID allocated for the instruction cache (L3CODE).
+
Memory bandwidth(MB) subdirectory contains the following files
with respect to allocation:
diff --git a/fs/resctrl/rdtgroup.c b/fs/resctrl/rdtgroup.c
index a2eea85aecc8..d7c4417b4516 100644
--- a/fs/resctrl/rdtgroup.c
+++ b/fs/resctrl/rdtgroup.c
@@ -1836,6 +1836,28 @@ static ssize_t mbm_local_bytes_config_write(struct kernfs_open_file *of,
return ret ?: nbytes;
}
+static int resctrl_io_alloc_show(struct kernfs_open_file *of,
+ struct seq_file *seq, void *v)
+{
+ struct resctrl_schema *s = rdt_kn_parent_priv(of->kn);
+ struct rdt_resource *r = s->res;
+
+ mutex_lock(&rdtgroup_mutex);
+
+ if (r->cache.io_alloc_capable) {
+ if (resctrl_arch_get_io_alloc_enabled(r))
+ seq_puts(seq, "enabled\n");
+ else
+ seq_puts(seq, "disabled\n");
+ } else {
+ seq_puts(seq, "not supported\n");
+ }
+
+ mutex_unlock(&rdtgroup_mutex);
+
+ return 0;
+}
+
/* rdtgroup information files for one cache resource. */
static struct rftype res_common_files[] = {
{
@@ -1926,6 +1948,12 @@ static struct rftype res_common_files[] = {
.kf_ops = &rdtgroup_kf_single_ops,
.seq_show = rdt_thread_throttle_mode_show,
},
+ {
+ .name = "io_alloc",
+ .mode = 0444,
+ .kf_ops = &rdtgroup_kf_single_ops,
+ .seq_show = resctrl_io_alloc_show,
+ },
{
.name = "max_threshold_occupancy",
.mode = 0644,
@@ -2095,6 +2123,15 @@ static void thread_throttle_mode_init(void)
RFTYPE_CTRL_INFO | RFTYPE_RES_MB);
}
+static void io_alloc_init(void)
+{
+ struct rdt_resource *r = resctrl_arch_get_resource(RDT_RESOURCE_L3);
+
+ if (r->cache.io_alloc_capable)
+ resctrl_file_fflags_init("io_alloc", RFTYPE_CTRL_INFO |
+ RFTYPE_RES_CACHE);
+}
+
void resctrl_file_fflags_init(const char *config, unsigned long fflags)
{
struct rftype *rft;
@@ -4282,6 +4319,8 @@ int resctrl_init(void)
thread_throttle_mode_init();
+ io_alloc_init();
+
ret = resctrl_mon_resource_init();
if (ret)
return ret;
--
2.34.1
