On 2016/07/28 23:26、David Ahern wrote: >> But that means we cannot handle preemption correctly as far as >> sched:sched_switch >> event uses TASK_STATE_MAX to mark preempted tasks. >> >> Should we stop using TASK_STATE_MAX for preempted tasks in ftrace and >> use (1 << 63) or something that doesn't change on kernel version instead? > > ftrace printing is within the kernel so it has consistency. Agreed.
> It is the save data and analyze later use case that can not assume > TASK_STATE_MAX means preemption since the value of TASK_STATE_MAX is kernel > version dependent. That means we cannot measure delay by preemption using perf sched latency. :( It might be helpful if the preemption mark becomes kernel-version-independent at least for future kernel version.. Anyway, this time I will post the patch to fix only invalid conversion issue of task state with this patch. Thanks, Tomoki Sekiyama
