On Tue, Mar 26, 2019 at 02:35:49PM -0400, Joel Fernandes wrote: > On Tue, Mar 26, 2019 at 09:01:40AM -0700, Paul E. McKenney wrote: > > On Mon, Mar 25, 2019 at 06:40:17PM -0400, Joel Fernandes wrote: > > > On Mon, Mar 25, 2019 at 12:42 PM Paul E. McKenney <paulmck@xxxxxxxxxxxxx> wrote: > > > > > > > > On Mon, Mar 25, 2019 at 12:33:37PM -0400, Joel Fernandes wrote: > > > > > On Mon, Mar 25, 2019 at 11:02 AM Paul E. McKenney <paulmck@xxxxxxxxxxxxx> wrote: > > > > > > > > > > > > On Fri, Mar 22, 2019 at 11:46:19PM -0400, Joel Fernandes (Google) wrote: > > > > > > > The rcutorture jitter.sh script selects a random CPU but does not check > > > > > > > if it is offline or online. This leads to taskset errors many times. On > > > > > > > my machine, hyper threading is disabled so half the cores are offline > > > > > > > causing taskset errors a lot of times. Let us fix this by checking from > > > > > > > only the online CPUs on the system. > > > > > > > > > > > > > > Signed-off-by: Joel Fernandes (Google) <joel@xxxxxxxxxxxxxxxxx> > > > > > > > > > > > > Good catch! > > > > > > > > > > > > Please see below for one suggestion for simplification. > > > > > > > > > > > > Thanx, Paul > > > > > > > > > > > > > --- > > > > > > > tools/testing/selftests/rcutorture/bin/jitter.sh | 11 ++++++++++- > > > > > > > 1 file changed, 10 insertions(+), 1 deletion(-) > > > > > > > > > > > > > > diff --git a/tools/testing/selftests/rcutorture/bin/jitter.sh b/tools/testing/selftests/rcutorture/bin/jitter.sh > > > > > > > index 3633828375e3..53bf9d99b5cd 100755 > > > > > > > --- a/tools/testing/selftests/rcutorture/bin/jitter.sh > > > > > > > +++ b/tools/testing/selftests/rcutorture/bin/jitter.sh > > > > > > > @@ -47,10 +47,19 @@ do > > > > > > > exit 0; > > > > > > > fi > > > > > > > > > > > > > > - # Set affinity to randomly selected CPU > > > > > > > + # Set affinity to randomly selected online CPU > > > > > > > cpus=`ls /sys/devices/system/cpu/*/online | > > > > > > > > > > > > cpus=`grep 1 /sys/devices/system/cpu/*/online | > > > > > > > > > > Yes, this is better. Lets do it this way :) > > > > > > > > > > > > sed -e 's,/[^/]*$,,' -e 's/^[^0-9]*//' | > > > > > > > grep -v '^0*$'` > > > > > > > > > > > > Of course, now I have no idea why I excluded CPU 0... :-/ > > > > > > > > > > Yes, I was wondering as well about that :-) > > > > > > > > Please feel free to try including CPU 0 and running the set of single-CPU > > > > rcutorture scenarios. ;-) > > > > > > Will do and then will update the patch by adding the CPU back, if all > > > is well. Thanks. > > > > And rcutorture doesn't like the rcu_is_cpu_rrupt_from_idle() patch on > > scenarios SRCU-P, TASKS01, and TREE05, which are the Tree RCU scenarios > > that enable CONFIG_PROVE_RCU. The compiler error is: > > > > kernel/rcu/tree.c:391:2: error: implicit declaration of function ‘_this_cpu_read’ [-Werror=implicit-function-declaration] > > > > My guess is that the initial underscore needs to go. I will drop > > these two patches in favor of an update from you. ;-) > > Sorry, I fixed that up and running tests now. > > By the way, may be you decided to not run the jitter on CPU0 just because on > some systems, CPU0 does not have an 'online' file? In this case, the grep may > throw errors I guess which troubles the script. > > From the old cpu hotplug docs, I found that if CONFIG_BOOTPARAM_HOTPLUG_CPU0 > or cpu0_hotplug boot command line option is not passed, then cpu0 cannot be > offlined in which case, presumably the 'online' file will be missing, like > some systems I am testing on. Never mind, the "*" in your path search would take care of not erroring out :-) The other reason you may have done it is for making the jitter be consistent across systems that can offline CPU0, and the others that can't :-). I am just guessing. Any way, I will just add back CPU0 forcefully to the cpus list in my testing, without checking for the online file existence, and see what happens :-) If there's no smoke, then I'll roll that into a patch and send it out. thanks.
