System calls

On Linux and Android (userdebug builds only) Perfetto can keep track of system calls.

Right now only the syscall number is recorded in the trace, the arguments are not stored to limit the trace size overhead.

At import time, the Trace Processor uses an internal syscall mapping table, currently supporting x86, x86_64, ArmEabi, aarch32 and aarch64. These tables are generated through the extract_linux_syscall_tables script.

UI

At the UI level system calls are shown inlined with the per-thread slice tracks:

SQL

At the SQL level, syscalls are no different than any other userspace slice event. They get interleaved in the per-thread slice stack and can be easily filtered by looking for the ‘sys_’ prefix:

select ts, dur, t.name as thread, s.name, depth from slices as s
left join thread_track as tt on s.track_id = tt.id
left join thread as t on tt.utid = t.utid
where s.name like 'sys_%'

ts	dur	thread	name
856325324372751	439867648	s.nexuslauncher	sys_epoll_pwait
856325324376970	990	FpsThrottlerThr	sys_recvfrom
856325324378376	2657	surfaceflinger	sys_ioctl
856325324419574	1250	android.anim.lf	sys_recvfrom
856325324428168	27344	android.anim.lf	sys_ioctl
856325324451345	573	FpsThrottlerThr	sys_getuid

TraceConfig

data_sources: {
    config {
        name: "linux.ftrace"
        ftrace_config {
            ftrace_events: "raw_syscalls/sys_enter"
            ftrace_events: "raw_syscalls/sys_exit"
        }
    }
}