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Groups > linux.kernel > #1501224

[PATCH v4 17/18] x86/intel_rdt: Add scheduler hook

From "Fenghua Yu" <fenghua.yu@intel.com>
Newsgroups linux.kernel
Subject [PATCH v4 17/18] x86/intel_rdt: Add scheduler hook
Date 2016-10-15 01:20 +0200
Message-ID <ssjVD-7Za-23@gated-at.bofh.it> (permalink)
References <ssjVD-7Za-5@gated-at.bofh.it>
Organization linux.* mail to news gateway

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From: Fenghua Yu <fenghua.yu@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.yu@intel.com>
Signed-off-by: Tony Luck <tony.luck@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 8435ec6..863e838 100644
--- a/arch/x86/include/asm/intel_rdt.h
+++ b/arch/x86/include/asm/intel_rdt.h
@@ -4,6 +4,9 @@
 #define IA32_L3_CBM_BASE	0xc90
 #define IA32_L2_CBM_BASE	0xd10
 
+#ifdef CONFIG_INTEL_RDT_A
+#include <asm/intel_rdt_common.h>
+
 /**
  * struct rdtgroup - store rdtgroup's data in resctrl file system.
  * @kn:				kernfs node
@@ -162,4 +165,42 @@ 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_A */
 #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 556a426..933bcb4 100644
--- a/arch/x86/kernel/cpu/intel_rdt.c
+++ b/arch/x86/kernel/cpu/intel_rdt.c
@@ -29,7 +29,6 @@
 #include <linux/cacheinfo.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 6787fd8..62883af 100644
--- a/arch/x86/kernel/cpu/intel_rdt_rdtgroup.c
+++ b/arch/x86/kernel/cpu/intel_rdt_rdtgroup.c
@@ -299,6 +299,9 @@ 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

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Thread

[PATCH v4 00/18] Intel Cache Allocation Technology "Fenghua Yu" <fenghua.yu@intel.com> - 2016-10-15 01:20 +0200
  [PATCH v4 02/18] cacheinfo: Introduce cache id "Fenghua Yu" <fenghua.yu@intel.com> - 2016-10-15 01:20 +0200
    Re: [PATCH v4 02/18] cacheinfo: Introduce cache id Thomas Gleixner <tglx@linutronix.de> - 2016-10-17 12:40 +0200
  [PATCH v4 16/18] x86/intel_rdt: Add schemata file "Fenghua Yu" <fenghua.yu@intel.com> - 2016-10-15 01:20 +0200
    Re: [PATCH v4 16/18] x86/intel_rdt: Add schemata file Thomas Gleixner <tglx@linutronix.de> - 2016-10-18 00:40 +0200
  [PATCH v4 13/18] x86/intel_rdt: Add mkdir to resctrl file system "Fenghua Yu" <fenghua.yu@intel.com> - 2016-10-15 01:20 +0200
    Re: [PATCH v4 13/18] x86/intel_rdt: Add mkdir to resctrl file  system Thomas Gleixner <tglx@linutronix.de> - 2016-10-17 23:20 +0200
      Re: [PATCH v4 13/18] x86/intel_rdt: Add mkdir to resctrl file system "Luck, Tony" <tony.luck@intel.com> - 2016-10-18 00:00 +0200
        Re: [PATCH v4 13/18] x86/intel_rdt: Add mkdir to resctrl file  system Thomas Gleixner <tglx@linutronix.de> - 2016-10-18 01:00 +0200
          RE: [PATCH v4 13/18] x86/intel_rdt: Add mkdir to resctrl file  system Thomas Gleixner <tglx@linutronix.de> - 2016-10-18 01:10 +0200
            RE: [PATCH v4 13/18] x86/intel_rdt: Add mkdir to resctrl file system "Luck, Tony" <tony.luck@intel.com> - 2016-10-18 01:20 +0200
              RE: [PATCH v4 13/18] x86/intel_rdt: Add mkdir to resctrl file  system Thomas Gleixner <tglx@linutronix.de> - 2016-10-18 01:30 +0200
          RE: [PATCH v4 13/18] x86/intel_rdt: Add mkdir to resctrl file system "Luck, Tony" <tony.luck@intel.com> - 2016-10-18 01:10 +0200
      Re: [PATCH v4 13/18] x86/intel_rdt: Add mkdir to resctrl file system Fenghua Yu <fenghua.yu@intel.com> - 2016-10-18 00:20 +0200
        Re: [PATCH v4 13/18] x86/intel_rdt: Add mkdir to resctrl file  system Thomas Gleixner <tglx@linutronix.de> - 2016-10-18 01:30 +0200
          Re: [PATCH v4 13/18] x86/intel_rdt: Add mkdir to resctrl file system "Luck, Tony" <tony.luck@intel.com> - 2016-10-18 01:40 +0200
            Re: [PATCH v4 13/18] x86/intel_rdt: Add mkdir to resctrl file system Fenghua Yu <fenghua.yu@intel.com> - 2016-10-18 02:00 +0200
            Re: [PATCH v4 13/18] x86/intel_rdt: Add mkdir to resctrl file  system Thomas Gleixner <tglx@linutronix.de> - 2016-10-18 12:50 +0200
  [PATCH v4 08/18] x86/intel_rdt: Pick up L3/L2 RDT parameters from CPUID "Fenghua Yu" <fenghua.yu@intel.com> - 2016-10-15 01:20 +0200
    Re: [PATCH v4 08/18] x86/intel_rdt: Pick up L3/L2 RDT parameters  from CPUID Thomas Gleixner <tglx@linutronix.de> - 2016-10-17 15:50 +0200
      Re: [PATCH v4 08/18] x86/intel_rdt: Pick up L3/L2 RDT parameters  from CPUID Fenghua Yu <fenghua.yu@intel.com> - 2016-10-17 17:10 +0200
        Re: [PATCH v4 08/18] x86/intel_rdt: Pick up L3/L2 RDT parameters  from CPUID "Luck, Tony" <tony.luck@intel.com> - 2016-10-17 18:40 +0200
          RE: [PATCH v4 08/18] x86/intel_rdt: Pick up L3/L2 RDT parameters  from CPUID "Yu, Fenghua" <fenghua.yu@intel.com> - 2016-10-17 18:50 +0200
            Re: [PATCH v4 08/18] x86/intel_rdt: Pick up L3/L2 RDT parameters  from CPUID "Luck, Tony" <tony.luck@intel.com> - 2016-10-17 22:30 +0200
          Re: [PATCH v4 08/18] x86/intel_rdt: Pick up L3/L2 RDT parameters  from CPUID Thomas Gleixner <tglx@linutronix.de> - 2016-10-17 19:10 +0200
        Re: [PATCH v4 08/18] x86/intel_rdt: Pick up L3/L2 RDT parameters  from CPUID Thomas Gleixner <tglx@linutronix.de> - 2016-10-17 19:10 +0200
        Re: [PATCH v4 08/18] x86/intel_rdt: Pick up L3/L2 RDT parameters  from CPUID Thomas Gleixner <tglx@linutronix.de> - 2016-10-17 19:10 +0200
          Re: [PATCH v4 08/18] x86/intel_rdt: Pick up L3/L2 RDT parameters  from CPUID Fenghua Yu <fenghua.yu@intel.com> - 2016-10-17 20:20 +0200
  [PATCH v4 01/18] Documentation, ABI: Add a document entry for cache id "Fenghua Yu" <fenghua.yu@intel.com> - 2016-10-15 01:20 +0200
    Re: [PATCH v4 01/18] Documentation, ABI: Add a document entry for  cache id Thomas Gleixner <tglx@linutronix.de> - 2016-10-17 12:40 +0200
  [PATCH v4 18/18] MAINTAINERS: Add maintainer for Intel RDT resource allocation "Fenghua Yu" <fenghua.yu@intel.com> - 2016-10-15 01:20 +0200
  [PATCH v4 04/18] x86/intel_rdt: Feature discovery "Fenghua Yu" <fenghua.yu@intel.com> - 2016-10-15 01:20 +0200
  [PATCH v4 11/18] x86/intel_rdt: Add basic resctrl filesystem support "Fenghua Yu" <fenghua.yu@intel.com> - 2016-10-15 01:20 +0200
    Re: [PATCH v4 11/18] x86/intel_rdt: Add basic resctrl filesystem  support Thomas Gleixner <tglx@linutronix.de> - 2016-10-17 21:40 +0200
  [PATCH v4 05/18] Documentation, x86: Documentation for Intel resource allocation user interface "Fenghua Yu" <fenghua.yu@intel.com> - 2016-10-15 01:20 +0200
  [PATCH v4 17/18] x86/intel_rdt: Add scheduler hook "Fenghua Yu" <fenghua.yu@intel.com> - 2016-10-15 01:20 +0200
  [PATCH v4 14/18] x86/intel_rdt: Add cpus file "Fenghua Yu" <fenghua.yu@intel.com> - 2016-10-15 01:20 +0200
    Re: [PATCH v4 14/18] x86/intel_rdt: Add cpus file Thomas Gleixner <tglx@linutronix.de> - 2016-10-17 23:40 +0200
  [PATCH v4 12/18] x86/intel_rdt: Add "info" files to resctrl file system "Fenghua Yu" <fenghua.yu@intel.com> - 2016-10-15 01:20 +0200
    Re: [PATCH v4 12/18] x86/intel_rdt: Add "info" files to resctrl file  system Thomas Gleixner <tglx@linutronix.de> - 2016-10-17 21:50 +0200
  [PATCH v4 15/18] x86/intel_rdt: Add tasks files "Fenghua Yu" <fenghua.yu@intel.com> - 2016-10-15 01:20 +0200
    Re: [PATCH v4 15/18] x86/intel_rdt: Add tasks files Thomas Gleixner <tglx@linutronix.de> - 2016-10-18 00:10 +0200
      Re: [PATCH v4 15/18] x86/intel_rdt: Add tasks files "Luck, Tony" <tony.luck@intel.com> - 2016-10-18 00:20 +0200
  [PATCH v4 10/18] x86/intel_rdt: Build structures for each resource based on cache topology "Fenghua Yu" <fenghua.yu@intel.com> - 2016-10-15 01:20 +0200
    Re: [PATCH v4 10/18] x86/intel_rdt: Build structures for each resource  based on cache topology Thomas Gleixner <tglx@linutronix.de> - 2016-10-17 16:50 +0200
  [PATCH v4 03/18] x86, intel_cacheinfo: Enable cache id in x86 "Fenghua Yu" <fenghua.yu@intel.com> - 2016-10-15 01:20 +0200
    Re: [PATCH v4 03/18] x86, intel_cacheinfo: Enable cache id in x86 Thomas Gleixner <tglx@linutronix.de> - 2016-10-17 13:00 +0200
  [PATCH v4 07/18] x86/intel_rdt: Add Haswell feature discovery "Fenghua Yu" <fenghua.yu@intel.com> - 2016-10-15 01:20 +0200
    Re: [PATCH v4 07/18] x86/intel_rdt: Add Haswell feature discovery Thomas Gleixner <tglx@linutronix.de> - 2016-10-17 13:10 +0200

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