Messages in this thread | | | Date | Wed, 26 Feb 2020 13:10:40 -0800 | From | Andi Kleen <> | Subject | Re: [PATCH 2/2] x86/asm/delay: Introduce TPAUSE delay |
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On Wed, Feb 26, 2020 at 11:10:58AM -0800, Kyung Min Park wrote: > TPAUSE instructs the processor to enter an implementation-dependent > optimized state. The instruction execution wakes up when the time-stamp > counter reaches or exceeds the implicit EDX:EAX 64-bit input value. > The instruction execution also wakes up due to the expiration of > the operating system time-limit or by an external interrupt
This is actually a behavior change. Today's udelay() will continue after processing the interrupt. Your patches don't
I don't think it's a problem though. The interrupt will cause a long enough delay that exceed any reasonable udelay() requirements.
There would be a difference if someone did really long udelay()s, much longer than typical interrupts, in this case you might end up with a truncated udelay, but such long udelays are not something that we would encourage.
I don't think you need to change anything in the code, but should probably document this behavior.
-Andi
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