From 99a930b0d2b018f31474d69137f311ce3581a4c2 Mon Sep 17 00:00:00 2001 From: "Paul E. McKenney" Date: Tue, 30 Jun 2015 14:54:09 -0700 Subject: [PATCH] documentation: Describe new expedited stall warnings Signed-off-by: Paul E. McKenney --- Documentation/RCU/stallwarn.txt | 17 +++++++++++++++++ 1 file changed, 17 insertions(+) diff --git a/Documentation/RCU/stallwarn.txt b/Documentation/RCU/stallwarn.txt index 046f32637b95..efb9454875ab 100644 --- a/Documentation/RCU/stallwarn.txt +++ b/Documentation/RCU/stallwarn.txt @@ -163,6 +163,23 @@ message will be about three times the interval between the beginning of the stall and the first message. +Stall Warnings for Expedited Grace Periods + +If an expedited grace period detects a stall, it will place a message +like the following in dmesg: + + INFO: rcu_sched detected expedited stalls on CPUs: { 1 2 6 } 26009 jiffies s: 1043 + +This indicates that CPUs 1, 2, and 6 have failed to respond to a +reschedule IPI, that the expedited grace period has been going on for +26,009 jiffies, and that the expedited grace-period sequence counter is +1043. The fact that this last value is odd indicates that an expedited +grace period is in flight. + +It is entirely possible to see stall warnings from normal and from +expedited grace periods at about the same time from the same run. + + What Causes RCU CPU Stall Warnings? So your kernel printed an RCU CPU stall warning. The next question is -- 2.39.5