I would like to get my Core i7 CPU to enter sleep state just momentarily, for one millisecond or so from a batch file or executable.
I know sleep can be induced with SetSuspendState, but I'm looking for a solution that does not put the entire system to sleep, but just the CPU momentarily.
CPU is Core i7 3632QM, and OS is Windows 7 and 10. Thanks
Based on your comment about defeating some kind of shutdown every 30 mins, it sounds like you need the whole CPU (all cores) to sleep. We need much more detail on that to do more than guess about which sleep states will serve your purpose and which won't.
Based on comments, it's likely that ACPI S3 sleep will be needed. Ross's comment about the hardware supporting an S1 sleep didn't mention an S2 (CPU actually powered down), so it's probably not even possible to power down just the CPU.
So your best bet is to look into programmatically doing a sleep/wake cycle, which is possible on at least some hardware. On Linux, the rtcwake command has an option to do that. I assume it programs a wakeup time into the BIOS's NVRAM before initiating a sleep. (I think there are only a few commonly-used formats/locations for storing this, so there's a good chance it's possible on your computer.)
Try a google search for wake up laptop at a certain time or something to find Windows equivalent of rtcwake. I didn't look at any of the hits, but they look promising.
I'm not an expert at this system power-state management stuff, but you probably need the system to enter an ACPI sleep state. S3 is the usual "suspend to RAM"; OSes that support suspend usually use this as their non-hibernate option.
For your use, maybe S1 or S2 will do (and anything less than this, like CPU power-saving C-states probably won't be sufficient, especially not states that are just per-core).
ACPI global sleep states (from Wikipedia). Systems are not required to implement all levels.
I'm not going to try to write Windows API function calls to do this. I wouldn't be surprised if there's an program for requesting Windows to enter S1 or S2 state (ideally with some kind of triggered wakeup).
@RossRidge says that the HM70 chipset does implement S1 sleep (and implies that it doesn't support an S2 sleep.) Since S1 doesn't power down the CPU, it may not reset the timer. Even a hypothetical S2 sleep might not do the trick, because the timer may be external to the CPU and/or managed by the BIOS.
Software exists to program the BIOS to wake at a certain time. That's one possible way to trigger coming out of suspend. So it might be possible to write a script that programs a wakeup time for 2 seconds in the future, then initiates a sleep.
@MargaretBloom comments that Chapter 14 of the Intel Manuals enumerates all the power-management capabilities. (See the x86 tag wiki for links). Also that a totally different workaround may be possible, by using SMM.
enter sleep state just momentarily, for one millisecond
1ms is about 3 million core clock cycles. That's not momentary for a computer, especially from an asm programming perspective.
You definitely don't want to write assembly by hand to enter these states. Instead, use your OS's existing ACPI interface. This is a big part of the reason that everyone downvoted the crap out of your followup question.
Other than short per-core sleeps from mwait, pause, and hlt insns, the OS needs to know what's going on. For more about pause, see this. There aren't specific instructions to enter deeper sleeps anyway; you program ACPI by writing to device registers in MMIO space.
When all cores are HLTed at the same time, the whole CPU can opportunistically power down more stuff until the next timer or other interrupt wakes it up again (this is or at least is related to ACPI C-states, as I understand it). But this happens all the time during normal operation, because modern OSes run HLT on cores that are idle. The only interesting thing you could do here is get the CPU to sleep like this occasionally even if the system was running some CPU-intensive processes. (e.g. some threads with non-idle priority that run hlt in a loop). Since HLT is a privileged instruction, this would require a kernel thread or a syscall. You probably can't actually raise the priority of the system idle process so it steals time from other runable processes.
This may be an oversimplification: I haven't looked at kernel idle tasks recently to see if they still just run HLT when they want the current core to sleep until the next interrupt. For a while (when CPU power management was in its infancy) idle loops used to run some other stuff to enter a low-power C-state. But HLT may do that now.