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-rw-r--r--Documentation/sysctl/kernel.txt50
1 files changed, 40 insertions, 10 deletions
diff --git a/Documentation/sysctl/kernel.txt b/Documentation/sysctl/kernel.txt
index ccd42589e124..ab7d16efa96b 100644
--- a/Documentation/sysctl/kernel.txt
+++ b/Documentation/sysctl/kernel.txt
@@ -70,12 +70,12 @@ show up in /proc/sys/kernel:
70- shmall 70- shmall
71- shmmax [ sysv ipc ] 71- shmmax [ sysv ipc ]
72- shmmni 72- shmmni
73- softlockup_thresh
74- stop-a [ SPARC only ] 73- stop-a [ SPARC only ]
75- sysrq ==> Documentation/sysrq.txt 74- sysrq ==> Documentation/sysrq.txt
76- tainted 75- tainted
77- threads-max 76- threads-max
78- unknown_nmi_panic 77- unknown_nmi_panic
78- watchdog_thresh
79- version 79- version
80 80
81============================================================== 81==============================================================
@@ -427,6 +427,32 @@ This file shows up if CONFIG_DEBUG_STACKOVERFLOW is enabled.
427 427
428============================================================== 428==============================================================
429 429
430perf_cpu_time_max_percent:
431
432Hints to the kernel how much CPU time it should be allowed to
433use to handle perf sampling events. If the perf subsystem
434is informed that its samples are exceeding this limit, it
435will drop its sampling frequency to attempt to reduce its CPU
436usage.
437
438Some perf sampling happens in NMIs. If these samples
439unexpectedly take too long to execute, the NMIs can become
440stacked up next to each other so much that nothing else is
441allowed to execute.
442
4430: disable the mechanism. Do not monitor or correct perf's
444 sampling rate no matter how CPU time it takes.
445
4461-100: attempt to throttle perf's sample rate to this
447 percentage of CPU. Note: the kernel calculates an
448 "expected" length of each sample event. 100 here means
449 100% of that expected length. Even if this is set to
450 100, you may still see sample throttling if this
451 length is exceeded. Set to 0 if you truly do not care
452 how much CPU is consumed.
453
454==============================================================
455
430 456
431pid_max: 457pid_max:
432 458
@@ -604,15 +630,6 @@ without users and with a dead originative process will be destroyed.
604 630
605============================================================== 631==============================================================
606 632
607softlockup_thresh:
608
609This value can be used to lower the softlockup tolerance threshold. The
610default threshold is 60 seconds. If a cpu is locked up for 60 seconds,
611the kernel complains. Valid values are 1-60 seconds. Setting this
612tunable to zero will disable the softlockup detection altogether.
613
614==============================================================
615
616tainted: 633tainted:
617 634
618Non-zero if the kernel has been tainted. Numeric values, which 635Non-zero if the kernel has been tainted. Numeric values, which
@@ -648,3 +665,16 @@ that time, kernel debugging information is displayed on console.
648 665
649NMI switch that most IA32 servers have fires unknown NMI up, for 666NMI switch that most IA32 servers have fires unknown NMI up, for
650example. If a system hangs up, try pressing the NMI switch. 667example. If a system hangs up, try pressing the NMI switch.
668
669==============================================================
670
671watchdog_thresh:
672
673This value can be used to control the frequency of hrtimer and NMI
674events and the soft and hard lockup thresholds. The default threshold
675is 10 seconds.
676
677The softlockup threshold is (2 * watchdog_thresh). Setting this
678tunable to zero will disable lockup detection altogether.
679
680==============================================================