On Mon, 2016-09-19 at 12:47 +0800, Simon Guo wrote: > On Wed, Sep 14, 2016 at 06:02:16PM +1000, Cyril Bur wrote: > > > > @@ -954,8 +963,16 @@ static inline void __switch_to_tm(struct > > task_struct *prev, > > struct task_struct *new) > > { > > if (cpu_has_feature(CPU_FTR_TM)) { > > - tm_enable(); > > - tm_reclaim_task(prev); > > + if (tm_enabled(prev) || tm_enabled(new)) > > + tm_enable(); > > + > > + if (tm_enabled(prev)) { > > + prev->thread.load_tm++; > > + tm_reclaim_task(prev); > > + if (!MSR_TM_ACTIVE(prev->thread.regs->msr) > > && prev->thread.load_tm == 0) > > + prev->thread.regs->msr &= ~MSR_TM; > > + } > Hi Cyril, > > If MSR_TM_ACTIVE(), is it better to reset load_tm to 0? > Other looks good to me. >
Doing so would extend the window that we keep TM enabled for when we might not need to. It is possible that we could assume that if MSR_TM_ACTIVE() then they're in codepathes that will reuse TM again soon so load_tm = 0 could be a good idea but there's really no way to know. Food for thought I guess... Maybe? Good thought, Cyril > Thanks, > - Simon