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Subject[PATCH 4/6] x86/intel_rdt/mba_sc: Add schemata support
Date
Currently user specifies the maximum memory bandwidth percentage per
domain in the "schemata" file. When user updates the schemata, kernel
writes the corresponding b/w percentage values to the
IA32_MBA_THRTL_MSR.

When MBA is expressed in MegaBytes(MB), the schemata format is changed
to have the per package memory b/w in MB instead of being specified in
b/w percentage. The b/w percentage values are only <= 100 and the b/w in
MB could be upto U32_MAX. We do not write the MSRs when the schemata is
updated as that is handled separately after the m/w in MB is converted
to b/w in percentage values.

Signed-off-by: Vikas Shivappa <vikas.shivappa@linux.intel.com>
---
arch/x86/kernel/cpu/intel_rdt.c | 10 +++++++++-
arch/x86/kernel/cpu/intel_rdt_ctrlmondata.c | 10 ++++++++--
2 files changed, 17 insertions(+), 3 deletions(-)

diff --git a/arch/x86/kernel/cpu/intel_rdt.c b/arch/x86/kernel/cpu/intel_rdt.c
index 8a32561..8a12d26 100644
--- a/arch/x86/kernel/cpu/intel_rdt.c
+++ b/arch/x86/kernel/cpu/intel_rdt.c
@@ -179,7 +179,7 @@ struct rdt_resource rdt_resources_all[] = {
.msr_update = mba_wrmsr,
.cache_level = 3,
.parse_ctrlval = parse_bw,
- .format_str = "%d=%*d",
+ .format_str = "%d=%*u",
.fflags = RFTYPE_RES_MB,
},
};
@@ -356,6 +356,14 @@ static u32 delay_bw_map(unsigned long bw, struct rdt_resource *r)
{
unsigned int i;

+ /*
+ * The ctrl_val should not be written when
+ * MBA is expressed in Megabytes because the Megabyte value
+ * need to be first converted to delay values that can be
+ * programmed to the MSR.
+ */
+ WARN_ON(is_mba_MBctrl());
+
/* Write the delay values for mba. */
for (i = m->low; i < m->high; i++)
wrmsrl(r->msr_base + i, delay_bw_map(d->ctrl_val[i], r));
diff --git a/arch/x86/kernel/cpu/intel_rdt_ctrlmondata.c b/arch/x86/kernel/cpu/intel_rdt_ctrlmondata.c
index 23e1d5c..6372e4f 100644
--- a/arch/x86/kernel/cpu/intel_rdt_ctrlmondata.c
+++ b/arch/x86/kernel/cpu/intel_rdt_ctrlmondata.c
@@ -53,7 +53,8 @@ static bool bw_validate(char *buf, unsigned long *data, struct rdt_resource *r)
return false;
}

- if (bw < r->membw.min_bw || bw > r->default_ctrl) {
+ if ((bw < r->membw.min_bw || bw > r->default_ctrl) &&
+ !is_mba_MBctrl()) {
rdt_last_cmd_printf("MB value %ld out of range [%d,%d]\n", bw,
r->membw.min_bw, r->default_ctrl);
return false;
@@ -194,7 +195,12 @@ static int update_domains(struct rdt_resource *r, int closid)
d->ctrl_val[closid] = d->new_ctrl;
}
}
- if (cpumask_empty(cpu_mask))
+
+ /*
+ * Avoid writing the control msr with control values when
+ * MBA is expressed in Megabytes.
+ */
+ if (cpumask_empty(cpu_mask) || is_mba_MBctrl())
goto done;
cpu = get_cpu();
/* Update CBM on this cpu if it's in cpu_mask. */
--
1.9.1
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