On Mon, Feb 24, 2020 at 06:01:01PM +0100, Sebastian Andrzej Siewior wrote: > The migrate_disable counter should not exceed 255 so it is enough to > store it in an 8bit field. > With this change we can move the `preempt_lazy_count' member into the > gap so the whole struct shrinks by 4 bytes to 12 bytes in total. > Remove the `padding' field, it is not needed. > Update the tracing fields in trace_define_common_fields() (it was > missing the preempt_lazy_count field). > > Signed-off-by: Sebastian Andrzej Siewior <bigeasy@xxxxxxxxxxxxx> > --- > v1…v2: > - drop the `padding' member > - update the members in trace_define_common_fields() to match struct > trace_entry. seems ok to me.. not sure we care, but just wanted to point out that there's a 'not described gap' in the sched_wakeup's format file and probably in other formats as well: # cat /sys/kernel/debug/tracing/events/sched/sched_wakeup/format name: sched_wakeup ID: 310 format: field:unsigned short common_type; offset:0; size:2; signed:0; field:unsigned char common_flags; offset:2; size:1; signed:0; field:unsigned char common_preempt_count; offset:3; size:1; signed:0; field:int common_pid; offset:4; size:4; signed:1; field:unsigned char common_migrate_disable; offset:8; size:1; signed:0; field:unsigned char common_preempt_lazy_count; offset:9; size:1; signed:0; field:char comm[16]; offset:12; size:16; signed:1; field:pid_t pid; offset:28; size:4; signed:1; field:int prio; offset:32; size:4; signed:1; field:int success; offset:36; size:4; signed:1; field:int target_cpu; offset:40; size:4; signed:1; there's "common_preempt_lazy_count" field on offset 9 with size 1: common_preempt_lazy_count; offset:9; size:1; followed by "comm" field on offset 12: field:char comm[16]; offset:12; size:16; signed:1; which makes 2 bytes gap in between, that might confuse some applications like bpftrace ;-) however there's still enough data to workaround that, so I'm ok with that thanks, jirka
