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X-Proofpoint-ORIG-GUID: xiZdPCmBUPZdNtKUnnQ4iG6zmEx7sloF X-Proofpoint-GUID: xiZdPCmBUPZdNtKUnnQ4iG6zmEx7sloF Sebastian Andrzej Siewior writes: > On 2024-10-07 09:46:09 [+0200], Peter Zijlstra wrote: >> Hi! >> >> During LPC Thomas reminded me that the lazy preemption stuff was not the= re yet. >> >> So here goes, robot says it builds, and I checked both a regular and PRE= EMPT_RT >> build boots and can change the mode. >> >> Please have a poke. > > While comparing this vs what I have: > - need_resched() > It checked both (tif_need_resched_lazy() || tif_need_resched()) while > now it only looks at tif_need_resched(). > Also ensured that raw_irqentry_exit_cond_resched() does not trigger on > lazy. > I guess you can argue both ways what makes sense, just noting=E2=80=A6 I think we want need_resched() to be only tif_need_resched(). That way preemption in lazy mode *only* happens at the user mode boundary. If the scheduler wants to preempt imminently, it just sets (or upgrades to) TIF_NEED_RESCHED. > - __account_cfs_rq_runtime() and hrtick_start_fair() > Both have a resched_curr() instead of resched_curr_lazy(). Is this on > purpose? > > This is actually the main difference (ignoring the moving the RT bits > and dynamic-sched). The lazy-resched is slightly different but it should > do the same thing. > I have also tracing and riscv bits which I port tomorrow, test and add > to your pile. > > Sebastian -- ankur