On 8/10/2022 10:23 PM, Joel Fernandes wrote: > > > On 8/8/2022 11:45 PM, Joel Fernandes (Google) wrote: >> Just a refresh of v3 with one additional debug patch. v3's cover letter is here: >> https://lore.kernel.org/all/20220713213237.1596225-1-joel@xxxxxxxxxxxxxxxxx/ >> >> I just started working on this again while I have some time during paternity >> leave ;-) So I thought I'll just send it out again. No other changes other >> than that 1 debug patch I added on the top. >> >> Next I am going to go refine the power results as mentioned in Paul's comments >> on the last cover letter. > > Side note: Here is another big selling point for call_rcu_lazy(). > Instead of _lazy(), if you just increased jiffies_till_first_fqs, and > slowed *all* call_rcu() down to achieve the same effect, that would > affect percpu refcounters switching to atomic-mode, for example. > > They switch to atomic mode by calling __percpu_ref_switch_mode() which > is called by percpu_ref_switch_to_atomic_sync().> > This will slow this call down for the full lazy duration which will slow > down suspend in blk_pre_runtime_suspend(). Correction while I am going on the record (got to be careful these days). It *might* slow down RCU for the full lazy duration, unless of course a fly-by rescue call_rcu() comes in. - Joel
