On Thu, Mar 21, 2019 at 07:01:37PM +0100 Peter Zijlstra wrote: > On Tue, Mar 19, 2019 at 09:00:05AM -0400, Phil Auld wrote: > > sched/fair: Limit sched_cfs_period_timer loop to avoid hard lockup > > > > With extremely short cfs_period_us setting on a parent task group with a > > large > > number of children the for loop in sched_cfs_period_timer can run until the > > watchdog fires. There is no guarantee that the call to hrtimer_forward_now() > > will ever return 0. The large number of children can make > > do_sched_cfs_period_timer() take longer than the period. > > > > > To prevent this we add protection to the loop that detects when the loop > > has run > > too many times and scales the period and quota up, proportionally, so that > > the timer > > can complete before then next period expires. This preserves the relative > > runtime > > quota while preventing the hard lockup. > > > > A warning is issued reporting this state and the new values. > > > > v2: Math reworked/simplified by Peter Zijlstra. > > > > Signed-off-by: Phil Auld <[email protected]> > > Cc: Ben Segall <[email protected]> > > Cc: Ingo Molnar <[email protected]> > > Cc: Peter Zijlstra (Intel) <[email protected]> > > Cc: Anton Blanchard <[email protected]> > > Thanks!
Thank you for your time and help. What do you think about Cc: stable? Cheers, Phil --
