Comment 5 for bug 1389077

There are no warnings whatsoever in my syslog file about thermal temperature.

I do see this message that seems to correspond with the slowdown:

    intel_powerclamp: Start idle injection to reduce power

I have tried the 3.18.0-031800rc3-generic kernel. After running for a few minutes, I did not see a problem. However, my PC soon froze. I rebooted and it froze again. There may not have been enough time for the idle injection to kick in, so I can't say if that kernel fixed the problem or not.

I then installed the 3.16.0-031600-generic kernel. I did not experience a noticeable slowdown, and I didn't observe any kidle_inject threads using top. However, looking at my dmesg, I see the following messages:

[ 353.440226] intel_powerclamp: Start idle injection to reduce power
[ 357.442949] intel_powerclamp: Stop forced idle injection
[ 389.455697] intel_powerclamp: Start idle injection to reduce power
[ 393.455967] intel_powerclamp: Stop forced idle injection
[ 397.478979] intel_powerclamp: Start idle injection to reduce power
[ 401.479785] intel_powerclamp: Stop forced idle injection
[ 548.344665] chrome[3265]: segfault at 1f8 ip 00007f7e8ac2863f sp 00007fffd9265480 error 4 in i965_dri.so[7f7e8a8d5000+51c000]
[ 548.954533] chrome[3372]: segfault at 1f8 ip 00007fede229f63f sp 00007ffff1dc0e90 error 4 in i965_dri.so[7fede1f4c000+51c000]
[ 549.152357] chrome[3382]: segfault at 1f8 ip 00007fd000a4163f sp 00007fff3537ea60 error 4 in i965_dri.so[7fd0006ee000+51c000]
[ 768.798349] intel_powerclamp: Start idle injection to reduce power
[ 772.800659] intel_powerclamp: Stop forced idle injection
[ 776.827334] intel_powerclamp: Start idle injection to reduce power
[ 780.826651] intel_powerclamp: Stop forced idle injection
[ 796.853437] intel_powerclamp: Start idle injection to reduce power
[ 800.852951] intel_powerclamp: Stop forced idle injection
[ 804.972279] intel_powerclamp: Start idle injection to reduce power
[ 808.972072] intel_powerclamp: Stop forced idle injection
[ 812.992079] intel_powerclamp: Start idle injection to reduce power
[ 816.993884] intel_powerclamp: Stop forced idle injection
[ 821.115992] intel_powerclamp: Start idle injection to reduce power
[ 841.124582] intel_powerclamp: Stop forced idle injection

Because I don't believe the idle injection should be enabled at all, I tagged this with the kernel-bug-exists-upstream tag.

One additional datapoint: I tested with the vmlinuz-3.13.0-39-generic kernel, and I saw the same problem.