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authorReinette Chatre <reinette.chatre@intel.com>2018-06-22 15:42:30 -0700
committerThomas Gleixner <tglx@linutronix.de>2018-06-24 15:35:48 +0200
commit6fc0de37f663278af160e8e1f0c38b27e6c06206 (patch)
tree2001f39bf5a067d0c43d2576f24ba6a2191999d7 /Documentation/x86
parentf3be1e7b2cf8bc096386a3588fc640b0db6b28d7 (diff)
downloadlinux-6fc0de37f663278af160e8e1f0c38b27e6c06206.tar.bz2
x86/intel_rdt: Limit C-states dynamically when pseudo-locking active
Deeper C-states impact cache content through shrinking of the cache or flushing entire cache to memory before reducing power to the cache. Deeper C-states will thus negatively impact the pseudo-locked regions. To avoid impacting pseudo-locked regions C-states are limited on pseudo-locked region creation so that cores associated with the pseudo-locked region are prevented from entering deeper C-states. This is accomplished by requesting a CPU latency target which will prevent the core from entering C6 across all supported platforms. Signed-off-by: Reinette Chatre <reinette.chatre@intel.com> Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Cc: fenghua.yu@intel.com Cc: tony.luck@intel.com Cc: vikas.shivappa@linux.intel.com Cc: gavin.hindman@intel.com Cc: jithu.joseph@intel.com Cc: dave.hansen@intel.com Cc: hpa@zytor.com Link: https://lkml.kernel.org/r/1ef4f99dd6ba12fa6fb44c5a1141e75f952b9cd9.1529706536.git.reinette.chatre@intel.com
Diffstat (limited to 'Documentation/x86')
-rw-r--r--Documentation/x86/intel_rdt_ui.txt4
1 files changed, 2 insertions, 2 deletions
diff --git a/Documentation/x86/intel_rdt_ui.txt b/Documentation/x86/intel_rdt_ui.txt
index bcd0a6d2fcf8..acac30b67c62 100644
--- a/Documentation/x86/intel_rdt_ui.txt
+++ b/Documentation/x86/intel_rdt_ui.txt
@@ -461,8 +461,8 @@ in the cache via carefully configuring the CAT feature and controlling
application behavior. There is no guarantee that data is placed in
cache. Instructions like INVD, WBINVD, CLFLUSH, etc. can still evict
“locked” data from cache. Power management C-states may shrink or
-power off cache. It is thus recommended to limit the processor maximum
-C-state, for example, by setting the processor.max_cstate kernel parameter.
+power off cache. Deeper C-states will automatically be restricted on
+pseudo-locked region creation.
It is required that an application using a pseudo-locked region runs
with affinity to the cores (or a subset of the cores) associated