On Thu, Sep 10, 2020 at 1:20 PM <paulmck@xxxxxxxxxx> wrote: > > From: "Paul E. McKenney" <paulmck@xxxxxxxxxx> > > The various RCU tasks flavors currently wait 100 milliseconds between each > grace period in order to prevent CPU-bound loops and to favor efficiency > over latency. However, RCU Tasks Trace needs to have a grace-period > latency of roughly 25 milliseconds, which is completely infeasible given > the 100-millisecond per-grace-period sleep. This commit therefore reduces > this sleep duration to 5 milliseconds (or one jiffy, whichever is longer) > in kernels built with CONFIG_TASKS_TRACE_RCU_READ_MB=y. The commit log is either misleading or wrong? If I read the code correctly in CONFIG_TASKS_TRACE_RCU_READ_MB=y case the existing HZ/10 "paranoid sleep" is preserved. It's for the MB=n case it is reduced to HZ/200. Also I don't understand why you're talking about milliseconds but all numbers are HZ based. HZ/10 gives different number of milliseconds depending on HZ.
