WFE performance busy wait improvement#195
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ShahriarAhnaf wants to merge 1 commit intorenode:masterfrom
Open
WFE performance busy wait improvement#195ShahriarAhnaf wants to merge 1 commit intorenode:masterfrom
ShahriarAhnaf wants to merge 1 commit intorenode:masterfrom
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Three changes to fix WFE correctness and performance: 1. tlib: Set event register (sev_pending) on exception return in do_v7m_exception_exit() and do_v7m_secure_return(), per ARMv7-M ARM B1.4.2. Without this, firmware using WFE + ISR-sets-RAM-flag patterns deadlocks when the interrupt fires before the CPU reaches WFE. 2. tlib: Set event register on exception entry in do_interrupt_v7m(), per ARMv7-M ARM B1.4.2. Needed for nested exception scenarios. 3. tlib: Check and consume event register inline in HELPER(wfe) before halting. If sev_pending is set, clear it and return immediately instead of entering the WFI halt path. 4. BaseCPU: Sleep for the full remaining quantum during WFI/WFE instead of only the real-time pacing delta. sleeper.Interrupt() from OnGPIO wakes the thread early when an IRQ arrives, so host CPU usage drops from 100% to near-idle during WFE/WFI wait loops.
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Change for WFE performance: