Hi, Since kernel release 3.17.3 and for all 3.18-rc releases Intel turbo boost for my Ivy Bridge cpu doesn't work after resume from suspend. After several test I found out, that reverting commit c034871712730a33e0267095f48b62eae958499c solved my issue.
do you modify any of the sysfs parameters related to intel_pstate before the suspend? do all p-states fail to work after the resume, or just states above the base (guaranteed) frequency? (you can check by running turbostat and watching if the frequency changes with changes in load)
My CPU can scale 1200-2400Mhz without turbo and up to 3200 with turbo enabled (for all cores) and it works like this until STR. After resume CPU can still scale 1200-2400 but not higher (TURBO not working).
I don't modify any intel_pstate related sysfs parameters.
is this still a problem when using the latest upstream kernel?
I've noticed this problem too since about 3.18. My CPU is Intel Sandy Bridge 2500K and just as the OP says. After starting up my computer the CPU scales up to 4200MHz. After resume from sleep it only goes up to 3300MHz. Sorry but I can't help with any kernel bisecting. My best is installing the kernel from .deb files.
Fixed in 3.19.x kernels.
Closing then, thanks!