[PATCH v4 -tip 2/3] tracing: make a snapshot feature available from userspace

Ftrace has a snapshot feature available from kernel space and latency tracers (e.g. irqsoff) are using it. This patch enables user applictions to take a snapshot via debugfs. Add "snapshot" debugfs file in "tracing" directory. snapshot: This is used to take a snapshot and to read the

[PATCH v4 -tip 2/3] tracing: make a snapshot feature available from userspace

Ftrace has a snapshot feature available from kernel space and latency tracers (e.g. irqsoff) are using it. This patch enables user applictions to take a snapshot via debugfs. Add snapshot debugfs file in tracing directory. snapshot: This is used to take a snapshot and to read the output of