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Subject[PATCH 17/28] x86/intel_rdt/cqm: Add cpus file support
Date
The cpus file is extended to support resource monitoring. This is used
to over-ride the RMID of the default group when running on specific
CPUs. It works similar to the resource control. The "cpus" and
"cpus_list" file is present in default group, ctrl_mon groups and
monitor groups.

Each "cpus" file or cpu_list file reads a cpumask or list showing which
CPUs belong to the resource group. By default all online cpus belong to
the default root group. A CPU can be present in one "ctrl_mon" and one
"monitor" group simultaneously. They can be added to a resource group by
writing the CPU to the file. When a CPU is added to a ctrl_mon group it
is automatically removed from the previous ctrl_mon group. A CPU can be
added to a monitor group only if it is present in the parent ctrl_mon
group and when a CPU is added to a monitor group, it is automatically
removed from the previous monitor group. When CPUs go offline, they are
automatically removed from the ctrl_mon and monitor groups.

Signed-off-by: Vikas Shivappa <vikas.shivappa@linux.intel.com>
---
arch/x86/kernel/cpu/intel_rdt_rdtgroup.c | 110 ++++++++++++++++++++++++++-----
1 file changed, 93 insertions(+), 17 deletions(-)

diff --git a/arch/x86/kernel/cpu/intel_rdt_rdtgroup.c b/arch/x86/kernel/cpu/intel_rdt_rdtgroup.c
index 7f8f52d..abc06ea 100644
--- a/arch/x86/kernel/cpu/intel_rdt_rdtgroup.c
+++ b/arch/x86/kernel/cpu/intel_rdt_rdtgroup.c
@@ -181,15 +181,17 @@ static int rdtgroup_cpus_show(struct kernfs_open_file *of,
/*
* This is safe against intel_rdt_sched_in() called from __switch_to()
* because __switch_to() is executed with interrupts disabled. A local call
- * from update_closid() is proteced against __switch_to() because
+ * from update_closid_rmid() is proteced against __switch_to() because
* preemption is disabled.
*/
-static void update_cpu_closid(void *info)
+static void update_cpu_closid_rmid(void *info)
{
struct rdtgroup *r = info;

- if (r)
+ if (r) {
this_cpu_write(rdt_cpu_default.closid, r->closid);
+ this_cpu_write(rdt_cpu_default.rmid, r->mon.rmid);
+ }

/*
* We cannot unconditionally write the MSR because the current
@@ -205,20 +207,72 @@ static void update_cpu_closid(void *info)
* Per task closids/rmids must have been set up before calling this function.
*/
static void
-update_closid(const struct cpumask *cpu_mask, struct rdtgroup *r)
+update_closid_rmid(const struct cpumask *cpu_mask, struct rdtgroup *r)
{
int cpu = get_cpu();

if (cpumask_test_cpu(cpu, cpu_mask))
- update_cpu_closid(r);
- smp_call_function_many(cpu_mask, update_cpu_closid, r, 1);
+ update_cpu_closid_rmid(r);
+ smp_call_function_many(cpu_mask, update_cpu_closid_rmid, r, 1);
put_cpu();
}

+static int cpus_mon_write(struct rdtgroup *rdtgrp, cpumask_var_t newmask,
+ cpumask_var_t tmpmask)
+{
+ struct rdtgroup *prgrp = rdtgrp->mon.parent, *crgrp;
+ struct list_head *head;
+
+ /* Check whether cpus belong to parent ctrl group */
+ cpumask_andnot(tmpmask, newmask, &prgrp->cpu_mask);
+ if (cpumask_weight(tmpmask))
+ return -EINVAL;
+
+ /* Check whether cpus are dropped from this group */
+ cpumask_andnot(tmpmask, &rdtgrp->cpu_mask, newmask);
+ if (cpumask_weight(tmpmask)) {
+ /* Give any dropped cpus to parent rdtgroup */
+ cpumask_or(&prgrp->cpu_mask, &prgrp->cpu_mask, tmpmask);
+ update_closid_rmid(tmpmask, prgrp);
+ }
+
+ /*
+ * If we added cpus, remove them from previous group that owned them
+ * and update per-cpu rmid
+ */
+ cpumask_andnot(tmpmask, newmask, &rdtgrp->cpu_mask);
+ if (cpumask_weight(tmpmask)) {
+ head = &prgrp->mon.crdtgrp_list;
+ list_for_each_entry(crgrp, head, mon.crdtgrp_list) {
+ if (crgrp == rdtgrp)
+ continue;
+ cpumask_andnot(&crgrp->cpu_mask, &crgrp->cpu_mask,
+ tmpmask);
+ }
+ update_closid_rmid(tmpmask, rdtgrp);
+ }
+
+ /* Done pushing/pulling - update this group with new mask */
+ cpumask_copy(&rdtgrp->cpu_mask, newmask);
+
+ return 0;
+}
+
+static void cpumask_rdtgrp_clear(struct rdtgroup *r, struct cpumask *m)
+{
+ struct rdtgroup *crgrp;
+
+ cpumask_andnot(&r->cpu_mask, &r->cpu_mask, m);
+ /* update the child mon group masks as well*/
+ list_for_each_entry(crgrp, &r->mon.crdtgrp_list, mon.crdtgrp_list)
+ cpumask_and(&crgrp->cpu_mask, &r->cpu_mask, &crgrp->cpu_mask);
+}
+
static int cpus_ctrl_write(struct rdtgroup *rdtgrp, cpumask_var_t newmask,
- cpumask_var_t tmpmask)
+ cpumask_var_t tmpmask, cpumask_var_t tmpmask1)
{
- struct rdtgroup *r;
+ struct rdtgroup *r, *crgrp;
+ struct list_head *head;

/* Check whether cpus are dropped from this group */
cpumask_andnot(tmpmask, &rdtgrp->cpu_mask, newmask);
@@ -230,33 +284,47 @@ static int cpus_ctrl_write(struct rdtgroup *rdtgrp, cpumask_var_t newmask,
/* Give any dropped cpus to rdtgroup_default */
cpumask_or(&rdtgroup_default.cpu_mask,
&rdtgroup_default.cpu_mask, tmpmask);
- update_closid(tmpmask, &rdtgroup_default);
+ update_closid_rmid(tmpmask, &rdtgroup_default);
}

/*
- * If we added cpus, remove them from previous group that owned them
- * and update per-cpu closid
+ * If we added cpus, remove them from previous group and
+ * the prev group's child groups that owned them
+ * and update per-cpu closid/rmid.
*/
cpumask_andnot(tmpmask, newmask, &rdtgrp->cpu_mask);
if (cpumask_weight(tmpmask)) {
list_for_each_entry(r, &rdt_all_groups, rdtgroup_list) {
if (r == rdtgrp)
continue;
- cpumask_andnot(&r->cpu_mask, &r->cpu_mask, tmpmask);
+ cpumask_and(tmpmask1, &r->cpu_mask, tmpmask);
+ if (cpumask_weight(tmpmask1))
+ cpumask_rdtgrp_clear(r, tmpmask1);
}
- update_closid(tmpmask, rdtgrp);
+ update_closid_rmid(tmpmask, rdtgrp);
}

/* Done pushing/pulling - update this group with new mask */
cpumask_copy(&rdtgrp->cpu_mask, newmask);

+ /*
+ * Clear child mon group masks since there is a new parent mask
+ * now and update the rmid for the cpus the child lost.
+ */
+ head = &rdtgrp->mon.crdtgrp_list;
+ list_for_each_entry(crgrp, head, mon.crdtgrp_list) {
+ cpumask_and(tmpmask, &rdtgrp->cpu_mask, &crgrp->cpu_mask);
+ update_closid_rmid(tmpmask, rdtgrp);
+ cpumask_clear(&crgrp->cpu_mask);
+ }
+
return 0;
}

static ssize_t rdtgroup_cpus_write(struct kernfs_open_file *of,
char *buf, size_t nbytes, loff_t off)
{
- cpumask_var_t tmpmask, newmask;
+ cpumask_var_t tmpmask, newmask, tmpmask1;
struct rdtgroup *rdtgrp;
int ret;

@@ -269,6 +337,11 @@ static ssize_t rdtgroup_cpus_write(struct kernfs_open_file *of,
free_cpumask_var(tmpmask);
return -ENOMEM;
}
+ if (!zalloc_cpumask_var(&tmpmask1, GFP_KERNEL)) {
+ free_cpumask_var(tmpmask);
+ free_cpumask_var(newmask);
+ return -ENOMEM;
+ }

rdtgrp = rdtgroup_kn_lock_live(of->kn);
if (!rdtgrp) {
@@ -292,7 +365,9 @@ static ssize_t rdtgroup_cpus_write(struct kernfs_open_file *of,
}

if (rdtgrp->type == RDTCTRL_GROUP)
- ret = cpus_ctrl_write(rdtgrp, newmask, tmpmask);
+ ret = cpus_ctrl_write(rdtgrp, newmask, tmpmask, tmpmask1);
+ else if (rdtgrp->type == RDTMON_GROUP)
+ ret = cpus_mon_write(rdtgrp, newmask, tmpmask);
else
ret = -EINVAL;

@@ -300,6 +375,7 @@ static ssize_t rdtgroup_cpus_write(struct kernfs_open_file *of,
rdtgroup_kn_unlock(of->kn);
free_cpumask_var(tmpmask);
free_cpumask_var(newmask);
+ free_cpumask_var(tmpmask1);

return ret ?: nbytes;
}
@@ -1114,7 +1190,7 @@ static void rmdir_all_sub(void)
}
/* Notify online CPUs to update per cpu storage and PQR_ASSOC MSR */
get_online_cpus();
- update_closid(cpu_online_mask, &rdtgroup_default);
+ update_closid_rmid(cpu_online_mask, &rdtgroup_default);
put_online_cpus();

kernfs_remove(kn_info);
@@ -1377,7 +1453,7 @@ static int rdtgroup_rmdir(struct kernfs_node *kn)
* task running on them.
*/
cpumask_or(tmpmask, tmpmask, &rdtgrp->cpu_mask);
- update_closid(tmpmask, NULL);
+ update_closid_rmid(tmpmask, NULL);

rdtgrp->flags = RDT_DELETED;
closid_free(rdtgrp->closid);
--
1.9.1
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