---

yaml
---
r: 167902
b: refs/heads/master
c: d4f452f
h: refs/heads/master
v: v3

[refs]

@@ -1,2 +1,2 @@
 ---
-refs/heads/master: 77de0846aed9d7a1b0ea65090620900d66fb5cfb
+refs/heads/master: d4f452f8259086028aa17d495deb735e056188f4

trunk/Documentation/hwmon/sysfs-interface

@@ -353,10 +353,20 @@ power[1-*]_average		Average power use
 				Unit: microWatt
 				RO
 
-power[1-*]_average_interval	Power use averaging interval
+power[1-*]_average_interval	Power use averaging interval.  A poll
+				notification is sent to this file if the
+				hardware changes the averaging interval.
 				Unit: milliseconds
 				RW
 
+power[1-*]_average_interval_max	Maximum power use averaging interval
+				Unit: milliseconds
+				RO
+
+power[1-*]_average_interval_min	Minimum power use averaging interval
+				Unit: milliseconds
+				RO
+
 power[1-*]_average_highest	Historical average maximum power use
 				Unit: microWatt
 				RO
@@ -365,6 +375,18 @@ power[1-*]_average_lowest	Historical average minimum power use
 				Unit: microWatt
 				RO
 
+power[1-*]_average_max		A poll notification is sent to
+				power[1-*]_average when power use
+				rises above this value.
+				Unit: microWatt
+				RW
+
+power[1-*]_average_min		A poll notification is sent to
+				power[1-*]_average when power use
+				sinks below this value.
+				Unit: microWatt
+				RW
+
 power[1-*]_input		Instantaneous power use
 				Unit: microWatt
 				RO
@@ -381,6 +403,39 @@ power[1-*]_reset_history	Reset input_highest, input_lowest,
 				average_highest and average_lowest.
 				WO
 
+power[1-*]_accuracy		Accuracy of the power meter.
+				Unit: Percent
+				RO
+
+power[1-*]_alarm		1 if the system is drawing more power than the
+				cap allows; 0 otherwise.  A poll notification is
+				sent to this file when the power use exceeds the
+				cap.  This file only appears if the cap is known
+				to be enforced by hardware.
+				RO
+
+power[1-*]_cap			If power use rises above this limit, the
+				system should take action to reduce power use.
+				A poll notification is sent to this file if the
+				cap is changed by the hardware.  The *_cap
+				files only appear if the cap is known to be
+				enforced by hardware.
+				Unit: microWatt
+				RW
+
+power[1-*]_cap_hyst		Margin of hysteresis built around capping and
+				notification.
+				Unit: microWatt
+				RW
+
+power[1-*]_cap_max		Maximum cap that can be set.
+				Unit: microWatt
+				RO
+
+power[1-*]_cap_min		Minimum cap that can be set.
+				Unit: microWatt
+				RO
+
 **********
 * Energy *
 **********

trunk/Documentation/vm/hwpoison.txt

@@ -0,0 +1,136 @@
+What is hwpoison?
+
+Upcoming Intel CPUs have support for recovering from some memory errors
+(``MCA recovery''). This requires the OS to declare a page "poisoned",
+kill the processes associated with it and avoid using it in the future.
+
+This patchkit implements the necessary infrastructure in the VM.
+
+To quote the overview comment:
+
+ * High level machine check handler. Handles pages reported by the
+ * hardware as being corrupted usually due to a 2bit ECC memory or cache
+ * failure.
+ *
+ * This focusses on pages detected as corrupted in the background.
+ * When the current CPU tries to consume corruption the currently
+ * running process can just be killed directly instead. This implies
+ * that if the error cannot be handled for some reason it's safe to
+ * just ignore it because no corruption has been consumed yet. Instead
+ * when that happens another machine check will happen.
+ *
+ * Handles page cache pages in various states. The tricky part
+ * here is that we can access any page asynchronous to other VM
+ * users, because memory failures could happen anytime and anywhere,
+ * possibly violating some of their assumptions. This is why this code
+ * has to be extremely careful. Generally it tries to use normal locking
+ * rules, as in get the standard locks, even if that means the
+ * error handling takes potentially a long time.
+ *
+ * Some of the operations here are somewhat inefficient and have non
+ * linear algorithmic complexity, because the data structures have not
+ * been optimized for this case. This is in particular the case
+ * for the mapping from a vma to a process. Since this case is expected
+ * to be rare we hope we can get away with this.
+
+The code consists of a the high level handler in mm/memory-failure.c,
+a new page poison bit and various checks in the VM to handle poisoned
+pages.
+
+The main target right now is KVM guests, but it works for all kinds
+of applications. KVM support requires a recent qemu-kvm release.
+
+For the KVM use there was need for a new signal type so that
+KVM can inject the machine check into the guest with the proper
+address. This in theory allows other applications to handle
+memory failures too. The expection is that near all applications
+won't do that, but some very specialized ones might.
+
+---
+
+There are two (actually three) modi memory failure recovery can be in:
+
+vm.memory_failure_recovery sysctl set to zero:
+	All memory failures cause a panic. Do not attempt recovery.
+	(on x86 this can be also affected by the tolerant level of the
+	MCE subsystem)
+
+early kill
+	(can be controlled globally and per process)
+	Send SIGBUS to the application as soon as the error is detected
+	This allows applications who can process memory errors in a gentle
+	way (e.g. drop affected object)
+	This is the mode used by KVM qemu.
+
+late kill
+	Send SIGBUS when the application runs into the corrupted page.
+	This is best for memory error unaware applications and default
+	Note some pages are always handled as late kill.
+
+---
+
+User control:
+
+vm.memory_failure_recovery
+	See sysctl.txt
+
+vm.memory_failure_early_kill
+	Enable early kill mode globally
+
+PR_MCE_KILL
+	Set early/late kill mode/revert to system default
+	arg1: PR_MCE_KILL_CLEAR: Revert to system default
+	arg1: PR_MCE_KILL_SET: arg2 defines thread specific mode
+		PR_MCE_KILL_EARLY: Early kill
+		PR_MCE_KILL_LATE:  Late kill
+		PR_MCE_KILL_DEFAULT: Use system global default
+PR_MCE_KILL_GET
+	return current mode
+
+
+---
+
+Testing:
+
+madvise(MADV_POISON, ....)
+	(as root)
+	Poison a page in the process for testing
+
+
+hwpoison-inject module through debugfs
+	/sys/debug/hwpoison/corrupt-pfn
+
+Inject hwpoison fault at PFN echoed into this file
+
+
+Architecture specific MCE injector
+
+x86 has mce-inject, mce-test
+
+Some portable hwpoison test programs in mce-test, see blow.
+
+---
+
+References:
+
+http://halobates.de/mce-lc09-2.pdf
+	Overview presentation from LinuxCon 09
+
+git://git.kernel.org/pub/scm/utils/cpu/mce/mce-test.git
+	Test suite (hwpoison specific portable tests in tsrc)
+
+git://git.kernel.org/pub/scm/utils/cpu/mce/mce-inject.git
+	x86 specific injector
+
+
+---
+
+Limitations:
+
+- Not all page types are supported and never will. Most kernel internal
+objects cannot be recovered, only LRU pages for now.
+- Right now hugepage support is missing.
+
+---
+Andi Kleen, Oct 2009
+