From: Fenghua Yu <fenghua...@intel.com>
Hook the x86 scheduler code to update closid based on whether the current
task is assigned to a specific closid or running on a CPU assigned to a
specific closid.
Signed-off-by: Fenghua Yu <fenghua...@intel.com>
Signed-off-by: Tony Luck <tony.l...@intel.com>
---
arch/x86/include/asm/intel_rdt.h | 41 ++++++++++++++++++++++++++++++++
arch/x86/kernel/cpu/intel_rdt.c | 1 -
arch/x86/kernel/cpu/intel_rdt_rdtgroup.c | 3 +++
arch/x86/kernel/process_32.c | 4 ++++
arch/x86/kernel/process_64.c | 4 ++++
5 files changed, 52 insertions(+), 1 deletion(-)
diff --git a/arch/x86/include/asm/intel_rdt.h b/arch/x86/include/asm/intel_rdt.h
index c052652..aefa3a6 100644
--- a/arch/x86/include/asm/intel_rdt.h
+++ b/arch/x86/include/asm/intel_rdt.h
@@ -1,6 +1,9 @@
#ifndef _ASM_X86_INTEL_RDT_H
#define _ASM_X86_INTEL_RDT_H
+#ifdef CONFIG_INTEL_RDT
+#include <asm/intel_rdt_common.h>
+
/**
* struct rdtgroup - store rdtgroup's data in resctrl file system.
* @kn: kernfs node
@@ -161,4 +164,42 @@ ssize_t rdtgroup_schemata_write(struct kernfs_open_file
*of,
char *buf, size_t nbytes, loff_t off);
int rdtgroup_schemata_show(struct kernfs_open_file *of,
struct seq_file *s, void *v);
+
+/*
+ * intel_rdt_sched_in() - Writes the task's CLOSid to IA32_PQR_MSR
+ *
+ * Following considerations are made so that this has minimal impact
+ * on scheduler hot path:
+ * - This will stay as no-op unless we are running on an Intel SKU
+ * which supports resource control and we enable by mounting the
+ * resctrl file system.
+ * - Caches the per cpu CLOSid values and does the MSR write only
+ * when a task with a different CLOSid is scheduled in.
+ */
+static inline void intel_rdt_sched_in(void)
+{
+ if (static_branch_likely(&rdt_enable_key)) {
+ struct intel_pqr_state *state = this_cpu_ptr(&pqr_state);
+ int closid;
+
+ /*
+ * If this task has a closid assigned, use it.
+ * Else use the closid assigned to this cpu.
+ */
+ closid = current->closid;
+ if (closid == 0)
+ closid = this_cpu_read(cpu_closid);
+
+ if (closid != state->closid) {
+ state->closid = closid;
+ wrmsr(MSR_IA32_PQR_ASSOC, state->rmid, closid);
+ }
+ }
+}
+
+#else
+
+static inline void intel_rdt_sched_in(void) {}
+
+#endif /* CONFIG_INTEL_RDT */
#endif /* _ASM_X86_INTEL_RDT_H */
diff --git a/arch/x86/kernel/cpu/intel_rdt.c b/arch/x86/kernel/cpu/intel_rdt.c
index 0b076d0..16a982e7 100644
--- a/arch/x86/kernel/cpu/intel_rdt.c
+++ b/arch/x86/kernel/cpu/intel_rdt.c
@@ -29,7 +29,6 @@
#include <linux/err.h>
#include <linux/cpuhotplug.h>
-#include <asm/intel_rdt_common.h>
#include <asm/intel-family.h>
#include <asm/intel_rdt.h>
diff --git a/arch/x86/kernel/cpu/intel_rdt_rdtgroup.c
b/arch/x86/kernel/cpu/intel_rdt_rdtgroup.c
index 4740b7e..b8c6e6e 100644
--- a/arch/x86/kernel/cpu/intel_rdt_rdtgroup.c
+++ b/arch/x86/kernel/cpu/intel_rdt_rdtgroup.c
@@ -282,6 +282,9 @@ static void move_myself(struct callback_head *head)
kfree(rdtgrp);
}
+ /* update PQR_ASSOC MSR to make resource group go into effect */
+ intel_rdt_sched_in();
+
kfree(callback);
}
diff --git a/arch/x86/kernel/process_32.c b/arch/x86/kernel/process_32.c
index d86be29..5495527 100644
--- a/arch/x86/kernel/process_32.c
+++ b/arch/x86/kernel/process_32.c
@@ -54,6 +54,7 @@
#include <asm/debugreg.h>
#include <asm/switch_to.h>
#include <asm/vm86.h>
+#include <asm/intel_rdt.h>
asmlinkage void ret_from_fork(void) __asm__("ret_from_fork");
asmlinkage void ret_from_kernel_thread(void) __asm__("ret_from_kernel_thread");
@@ -314,5 +315,8 @@ __switch_to(struct task_struct *prev_p, struct task_struct
*next_p)
this_cpu_write(current_task, next_p);
+ /* Load the Intel cache allocation PQR MSR. */
+ intel_rdt_sched_in();
+
return prev_p;
}
diff --git a/arch/x86/kernel/process_64.c b/arch/x86/kernel/process_64.c
index 63236d8..cdea7e3 100644
--- a/arch/x86/kernel/process_64.c
+++ b/arch/x86/kernel/process_64.c
@@ -49,6 +49,7 @@
#include <asm/debugreg.h>
#include <asm/switch_to.h>
#include <asm/xen/hypervisor.h>
+#include <asm/intel_rdt.h>
asmlinkage extern void ret_from_fork(void);
@@ -472,6 +473,9 @@ __switch_to(struct task_struct *prev_p, struct task_struct
*next_p)
loadsegment(ss, __KERNEL_DS);
}
+ /* Load the Intel cache allocation PQR MSR. */
+ intel_rdt_sched_in();
+
return prev_p;
}
--
2.5.0
