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Subject[PATCH 2/6] x86/intel_rdt/mba_sc: Enable/disable MBA software controller
Date
Currently user does memory bandwidth allocation(MBA) by specifying the
bandwidth in percentage via the resctrl schemata file:
"/sys/fs/resctrl/schemata"

Add a new mount option "mba_MBps" to enable the user to specify MBA
in MBps:

$mount -t resctrl resctrl [-o cdp[,cdpl2][mba_MBps]] /sys/fs/resctrl

Signed-off-by: Vikas Shivappa <vikas.shivappa@linux.intel.com>
---
arch/x86/kernel/cpu/intel_rdt.c | 8 ++++++++
arch/x86/kernel/cpu/intel_rdt.h | 3 +++
arch/x86/kernel/cpu/intel_rdt_rdtgroup.c | 30 ++++++++++++++++++++++++++++++
3 files changed, 41 insertions(+)

diff --git a/arch/x86/kernel/cpu/intel_rdt.c b/arch/x86/kernel/cpu/intel_rdt.c
index 2b65601..2a0931f 100644
--- a/arch/x86/kernel/cpu/intel_rdt.c
+++ b/arch/x86/kernel/cpu/intel_rdt.c
@@ -230,6 +230,14 @@ static inline void cache_alloc_hsw_probe(void)
rdt_alloc_capable = true;
}

+bool is_mba_sc(struct rdt_resource *r)
+{
+ if (!r)
+ return rdt_resources_all[RDT_RESOURCE_MBA].membw.mba_sc;
+
+ return r->membw.mba_sc;
+}
+
/*
* rdt_get_mb_table() - get a mapping of bandwidth(b/w) percentage values
* exposed to user interface and the h/w understandable delay values.
diff --git a/arch/x86/kernel/cpu/intel_rdt.h b/arch/x86/kernel/cpu/intel_rdt.h
index 3fd7a70..74aee0f 100644
--- a/arch/x86/kernel/cpu/intel_rdt.h
+++ b/arch/x86/kernel/cpu/intel_rdt.h
@@ -259,6 +259,7 @@ struct rdt_cache {
* @min_bw: Minimum memory bandwidth percentage user can request
* @bw_gran: Granularity at which the memory bandwidth is allocated
* @delay_linear: True if memory B/W delay is in linear scale
+ * @mba_sc: True if MBA software controller(mba_sc) is enabled
* @mb_map: Mapping of memory B/W percentage to memory B/W delay
*/
struct rdt_membw {
@@ -266,6 +267,7 @@ struct rdt_membw {
u32 min_bw;
u32 bw_gran;
u32 delay_linear;
+ bool mba_sc;
u32 *mb_map;
};

@@ -445,6 +447,7 @@ void mon_event_read(struct rmid_read *rr, struct rdt_domain *d,
void mbm_setup_overflow_handler(struct rdt_domain *dom,
unsigned long delay_ms);
void mbm_handle_overflow(struct work_struct *work);
+bool is_mba_sc(struct rdt_resource *r);
void cqm_setup_limbo_handler(struct rdt_domain *dom, unsigned long delay_ms);
void cqm_handle_limbo(struct work_struct *work);
bool has_busy_rmid(struct rdt_resource *r, struct rdt_domain *d);
diff --git a/arch/x86/kernel/cpu/intel_rdt_rdtgroup.c b/arch/x86/kernel/cpu/intel_rdt_rdtgroup.c
index fca759d..b9ceb13 100644
--- a/arch/x86/kernel/cpu/intel_rdt_rdtgroup.c
+++ b/arch/x86/kernel/cpu/intel_rdt_rdtgroup.c
@@ -1005,6 +1005,11 @@ static void l2_qos_cfg_update(void *arg)
wrmsrl(IA32_L2_QOS_CFG, *enable ? L2_QOS_CDP_ENABLE : 0ULL);
}

+static inline bool is_mba_linear(void)
+{
+ return rdt_resources_all[RDT_RESOURCE_MBA].membw.delay_linear;
+}
+
static int set_cache_qos_cfg(int level, bool enable)
{
void (*update)(void *arg);
@@ -1041,6 +1046,25 @@ static int set_cache_qos_cfg(int level, bool enable)
return 0;
}

+/*
+ * Enable or disable the MBA software controller
+ * which helps user specify bandwidth in MBps.
+ * MBA software controller is supported only if
+ * MBM is supported and MBA is in linear scale.
+ */
+static int set_mba_sc(bool mba_sc)
+{
+ struct rdt_resource *r = &rdt_resources_all[RDT_RESOURCE_MBA];
+
+ if (!is_mbm_enabled() || !is_mba_linear() ||
+ mba_sc == is_mba_sc(r))
+ return -1;
+
+ r->membw.mba_sc = mba_sc;
+
+ return 0;
+}
+
static int cdp_enable(int level, int data_type, int code_type)
{
struct rdt_resource *r_ldata = &rdt_resources_all[data_type];
@@ -1123,6 +1147,10 @@ static int parse_rdtgroupfs_options(char *data)
ret = cdpl2_enable();
if (ret)
goto out;
+ } else if (!strcmp(token, "mba_MBps")) {
+ ret = set_mba_sc(true);
+ if (ret)
+ goto out;
} else {
ret = -EINVAL;
goto out;
@@ -1445,6 +1473,8 @@ static void rdt_kill_sb(struct super_block *sb)
cpus_read_lock();
mutex_lock(&rdtgroup_mutex);

+ set_mba_sc(false);
+
/*Put everything back to default values. */
for_each_alloc_enabled_rdt_resource(r)
reset_all_ctrls(r);
--
1.9.1
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