Groups | Search | Server Info | Keyboard shortcuts | Login | Register [http] [https] [nntp] [nntps]

Groups > linux.kernel > #1563573 > unrolled thread

[PATCH v12 0/5] Enabling Ring 3 MONITOR/MWAIT feature for Knights Landing

Back to article view | Back to linux.kernel

Contents

  [PATCH v12 0/5] Enabling Ring 3 MONITOR/MWAIT feature for Knights Landing Grzegorz Andrejczuk <grzegorz.andrejczuk@intel.com> - 2017-01-20 14:30 +0100
    [PATCH v12 5/5] x86/cpufeature: enable RING3MWAIT for Knights Mill Grzegorz Andrejczuk <grzegorz.andrejczuk@intel.com> - 2017-01-20 14:30 +0100

#1563573 — [PATCH v12 0/5] Enabling Ring 3 MONITOR/MWAIT feature for Knights Landing

Following patches enable the use of the feature that allows
the Intel Xeon Phi x200 devices to use MONITOR/MWAIT instructions
outside ring 0. This feature allows userspace application to use
more efficient synchronization operations, which improves performance
and energy efficiency.

v12:
Removed unused define from msr-info.h
Added braces in define ELF_HWCAP
Set HWCAP2_RING3MWAIT bit only for boot cpu
Replaced set_bit by bit OR operator
Updated ring3mwait_disable return value
Rebased to kernel 4.10rc4
Updated commit messages

v11:
Removed warning from 32-bit build
Removed "This patch" from commit messages

v10:
Included Piotr's patch for Knights Mill
Included Dave's comments from internal review
Rewritten commit messages
Remove x86_64 requirement
Fixed kernel boot parameter description
Used set_bit to update HWCAP2 bit
Rebased to kernel 4.9

v9:
Removed PHI from defines

v8:
Fixed commit messages
Removed logging
Used msr_set/clear_bit functions instesd of wrmsrl
Fixed documentation
Renamed HWCAP2_PHIR3MWAIT to HWCAP2_RING3MWAIT

v7:
Change order of the patches, with this code looks cleaner.
Changed the name of MSR to MSR_MISC_FEATURE_ENABLES.
Used Word 3 25th bit to expose feature.

v6:

v5:
When phir3mwait=disable is cmdline switch off r3 mwait feature
Fix typos

v4:
Wrapped the enabling code by CONFIG_X86_64
Add documentation for phir3mwait=disable cmdline switch
Move probe_ function call from early_intel_init to intel_init
Fixed commit messages

v3:
Included Daves and Thomas comments

v2:
Check MSR before wrmsrl
Shortened names
Used Word 3 for feature init_scattered_cpuid_features()
Fixed commit messages

Grzegorz Andrejczuk (4):
  x86/msr: add MSR_MISC_FEATURE_ENABLES and RING3MWAIT bit
  x86/elf: add HWCAP2 to expose ring 3 MONITOR/MWAIT
  x86/cpufeature: add RING3MWAIT to CPU features
  x86/cpufeature: enable RING3MWAIT for Knights Landing

Piotr Luc (1):
  x86/cpufeature: enable RING3MWAIT for Knights Mill

 Documentation/admin-guide/kernel-parameters.txt |  4 +++
 arch/x86/include/asm/cpufeatures.h              |  2 +-
 arch/x86/include/asm/elf.h                      |  9 ++++++
 arch/x86/include/asm/msr-index.h                |  5 ++++
 arch/x86/include/uapi/asm/hwcap2.h              |  7 +++++
 arch/x86/kernel/cpu/common.c                    |  3 ++
 arch/x86/kernel/cpu/intel.c                     | 39 +++++++++++++++++++++++++
 7 files changed, 68 insertions(+), 1 deletion(-)
 create mode 100644 arch/x86/include/uapi/asm/hwcap2.h

-- 
2.5.1

[toc] | [next] | [standalone]

#1563574 — [PATCH v12 5/5] x86/cpufeature: enable RING3MWAIT for Knights Mill

From: Piotr Luc <piotr.luc@intel.com>

Enable ring 3 MONITOR/MWAIT for Intel Xeon Phi
codenamed Knights Mill. We can't guarantee that this (KNM)
will be the last CPU model that needs this hack.
But, we do recognize that this is far from optimal,
and there is an effort to ensure we don't keep doing
extending this hack forever.

Signed-off-by: Piotr Luc <piotr.luc@intel.com>
---
 arch/x86/kernel/cpu/intel.c | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/arch/x86/kernel/cpu/intel.c b/arch/x86/kernel/cpu/intel.c
index 213cbf0..b1b1af5 100644
--- a/arch/x86/kernel/cpu/intel.c
+++ b/arch/x86/kernel/cpu/intel.c
@@ -79,7 +79,9 @@ static void probe_xeon_phi_r3mwait(struct cpuinfo_x86 *c)
 	 * Ring 3 MONITOR/MWAIT feature cannot be detected without
 	 * cpu model and family comparison.
 	 */
-	if (c->x86 != 6 || c->x86_model != INTEL_FAM6_XEON_PHI_KNL)
+	if (c->x86 != 6 ||
+	   (c->x86_model != INTEL_FAM6_XEON_PHI_KNL &&
+	    c->x86_model != INTEL_FAM6_XEON_PHI_KNM))
 		return;
 
 	if (ring3mwait_disabled) {
-- 
2.5.1

[toc] | [prev] | [standalone]

Back to top | Article view | linux.kernel

csiph-web