On 02/20/2014 05:23 PM, Kevin Van Workum wrote:
Does anyone have a real-world application where setting intel_idle.max_cstate=0 and processor.max_cstate=0 actually makes a difference wrt application or network latency?
Stability actually with kernels from 3.2-3.10 and certain motherboard and processor combos. There are some *nasty* bugs in ASPM and other things, and we've observed crashes in cstate transitions in CPUs. The only way we've discovered to prevent these hangs in cpu_idle and other related functions was specifically to disable most of the cstate transitions.
Some of these stability issues would take down a variety of kernel subsystems. This led to very odd crashes where parts of the kernel were still working, but other parts we stuck in some work queue. Eventually the whole thing would crash.
Later 3.10.+ kernels don't seem to have these issues (I never bisected to find the bad/good transition points though).
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