On 09/26/2016 02:10 PM, Peter Zijlstra wrote: > On Mon, Sep 26, 2016 at 02:01:43PM +0200, Christian Borntraeger wrote: >> They applied ok on next from 9/13. Things go even worse. >> With this host configuration: >> >> CPU NODE BOOK SOCKET CORE L1d:L1i:L2d:L2i ONLINE CONFIGURED ADDRESS >> 0 0 0 0 0 0:0:0:0 yes yes 0 >> 1 0 0 0 0 1:1:1:1 yes yes 1 >> 2 0 0 0 1 2:2:2:2 yes yes 2 >> 3 0 0 0 1 3:3:3:3 yes yes 3 >> 4 0 0 1 2 4:4:4:4 yes yes 4 >> 5 0 0 1 2 5:5:5:5 yes yes 5 >> 6 0 0 1 3 6:6:6:6 yes yes 6 >> 7 0 0 1 3 7:7:7:7 yes yes 7 >> 8 0 0 1 4 8:8:8:8 yes yes 8 >> 9 0 0 1 4 9:9:9:9 yes yes 9 >> 10 0 0 1 5 10:10:10:10 yes yes 10 >> 11 0 0 1 5 11:11:11:11 yes yes 11 >> 12 0 0 1 6 12:12:12:12 yes yes 12 >> 13 0 0 1 6 13:13:13:13 yes yes 13 >> 14 0 0 1 7 14:14:14:14 yes yes 14 >> 15 0 0 1 7 15:15:15:15 yes yes 15 >> >> the guest was running either on 0-3 or on 4-15, but never >> used the full system. With group scheduling disabled everything was good >> again. So looks like that this bug has also some dependency on on the >> host topology. > > OK, so CPU affinities that unevenly straddle topology boundaries like > that are hard (and is generally not recommended), but its not
Ok so I created with cpu hotplug a symmetrical CPU topology: CPU NODE BOOK SOCKET CORE L1d:L1i:L2d:L2i ONLINE CONFIGURED ADDRESS 0 0 0 0 0 0:0:0:0 yes yes 0 1 0 0 0 0 1:1:1:1 yes yes 1 2 0 0 0 1 2:2:2:2 yes yes 2 3 0 0 0 1 3:3:3:3 yes yes 3 4 0 0 0 2 4:4:4:4 yes yes 4 5 0 0 0 2 5:5:5:5 yes yes 5 6 0 0 0 3 6:6:6:6 yes yes 6 7 0 0 0 3 7:7:7:7 yes yes 7 8 0 0 0 - ::: no yes 8 9 0 0 0 - ::: no yes 9 10 0 0 0 - ::: no yes 10 11 0 0 0 - ::: no yes 11 12 0 0 1 4 8:8:8:8 yes yes 12 13 0 0 1 4 9:9:9:9 yes yes 13 14 0 0 1 5 10:10:10:10 yes yes 14 15 0 0 1 5 11:11:11:11 yes yes 15 16 0 0 1 6 12:12:12:12 yes yes 16 17 0 0 1 6 13:13:13:13 yes yes 17 18 0 0 1 7 14:14:14:14 yes yes 18 19 0 0 1 7 15:15:15:15 yes yes 19 Same effect: Only half of the CPUs are used, but the number of guest CPUs == number of host cpus. Turns out that this is totally unrelated to this patch set, so it must be something else.
