On Tue, Mar 8, 2016 at 6:48 PM, Ingo Molnar <mi...@kernel.org> wrote: > > * Dmitry Vyukov <dvyu...@google.com> wrote: > >> On Tue, Mar 8, 2016 at 6:37 PM, Ingo Molnar <mi...@kernel.org> wrote: >> > >> > * Dmitry Vyukov <dvyu...@google.com> wrote: >> > >> >> > fomalhaut:~/go/src/github.com/google/syzkaller> ps aux | grep -i syz >> >> > mingo 1374 0.0 0.0 118476 2376 pts/2 S+ 18:23 0:00 grep >> >> > --color=auto -i syz >> >> > >> >> > and with no kernel messages in dmesg - and with a fully functional >> >> > system. >> >> > >> >> > I'm running the 16-task load on a 120 CPU system - should I increase it >> >> > to 120? >> >> > Does the code expect to saturate the system? >> >> >> >> No, it does not expect to saturate the system. Set "procs" to 480, or >> >> something like that. >> > >> > Does not seem to help much: >> > >> > fomalhaut:~> vmstat 10 >> > procs -----------memory---------- ---swap-- -----io---- -system-- >> > ------cpu----- >> > r b swpd free buff cache si so bi bo in cs us sy id >> > wa st >> > >> > 1 0 0 257465904 219940 4736092 0 0 0 102 16022 4396 0 >> > 1 99 0 0 >> > 2 0 0 257452144 220496 4755052 0 0 2 3649 14286 4627 0 >> > 1 99 0 0 >> > 2 0 0 257473408 221188 4770824 0 0 15 1898 17175 4474 0 >> > 1 99 0 0 >> > >> > Only around 1% system utilization. Should I go for 1,000 or more? :) >> > >> > Peter, do you experience with running syz-kaller on larger CPU count Intel >> > systems? >> >> >> Try to set "dropprivs": false in config. > > Things got a lot more lively after that! > > But most of the overhead seems to come from systemd trying to dump core or > something like that: > > 85872 mingo 20 0 34712 3016 2656 S 4.6 0.0 0:00.14 > systemd-coredum > 85440 mingo 20 0 34712 3028 2664 S 4.2 0.0 0:00.13 > systemd-coredum > 85751 mingo 20 0 34712 3076 2716 S 4.2 0.0 0:00.13 > systemd-coredum > 85840 mingo 20 0 34712 2988 2624 S 4.2 0.0 0:00.13 > systemd-coredum > 85861 mingo 20 0 34712 3080 2720 S 4.2 0.0 0:00.13 > systemd-coredum > 85954 mingo 20 0 34712 3028 2664 S 4.2 0.0 0:00.13 > systemd-coredum > > and I have: > > fomalhaut:~/go/src/github.com/google/syzkaller> ulimit -c > 0 > > weird ... Has any of you seen such behavior?
I have not seen it. Probably I need to directly disable core dumps within the syz-executor process.
