From: Dapeng Mi > Sent: 24 August 2022 10:11 > > TPAUSE is a new instruction on Intel processors which can instruct > processor enters a power/performance optimized state. Halt polling > uses PAUSE instruction to wait vCPU is waked up. The polling time > could be long and cause extra power consumption in some cases. > > Use TPAUSE to replace the PAUSE instruction in halt polling to get > a better power saving and performance. What is the effect on wakeup latency? Quite often that is far more important than a bit of power saving. The automatic entry of sleep states is a PITA already. Block 30 RT threads in cv_wait() and then do cv_broadcast(). Use ftrace to see just how long it takes the last thread to wake up. David - Registered Address Lakeside, Bramley Road, Mount Farm, Milton Keynes, MK1 1PT, UK Registration No: 1397386 (Wales)
