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(). This is why, we cannot assume call_rcu() users will mostly just want to free memory. There could be cases just like this, and just blanket slow down of call_rcu() might bite at unexpected times. I am going to add this as a selling point for selective lazyfication (hey I get to invent words while I'm inventing new features), to my cover letter and slides. - Joel > > Joel Fernandes (Google) (5): > rcu: Introduce call_rcu_lazy() API implementation > rcuscale: Add laziness and kfree tests > fs: Move call_rcu() to call_rcu_lazy() in some paths > rcutorture: Add test code for call_rcu_lazy() > debug: Toggle lazy at runtime and change flush jiffies > > Vineeth Pillai (1): > rcu: shrinker for lazy rcu > > fs/dcache.c | 4 +- > fs/eventpoll.c | 2 +- > fs/file_table.c | 2 +- > fs/inode.c | 2 +- > include/linux/rcu_segcblist.h | 1 + > include/linux/rcupdate.h | 6 + > include/linux/sched/sysctl.h | 3 + > kernel/rcu/Kconfig | 8 + > kernel/rcu/rcu.h | 12 + > kernel/rcu/rcu_segcblist.c | 15 +- > kernel/rcu/rcu_segcblist.h | 20 +- > kernel/rcu/rcuscale.c | 74 +++++- > kernel/rcu/rcutorture.c | 60 ++++- > kernel/rcu/tree.c | 131 ++++++---- > kernel/rcu/tree.h | 10 +- > kernel/rcu/tree_nocb.h | 246 +++++++++++++++--- > kernel/sysctl.c | 17 ++ > .../selftests/rcutorture/configs/rcu/CFLIST | 1 + > .../selftests/rcutorture/configs/rcu/TREE11 | 18 ++ > .../rcutorture/configs/rcu/TREE11.boot | 8 + > 20 files changed, 536 insertions(+), 104 deletions(-) > create mode 100644 tools/testing/selftests/rcutorture/configs/rcu/TREE11 > create mode 100644 tools/testing/selftests/rcutorture/configs/rcu/TREE11.boot > > -- > 2.37.1.559.g78731f0fdb-goog >
