• Anton Blanchard's avatar
    powerpc: tracing: Add powerpc tracepoints for timer entry and exit · 6795b85c
    Anton Blanchard authored
    We can monitor the effectiveness of our power management of both the
    kernel and hypervisor by probing the timer interrupt. For example, on
    this box we see 10.37s timer interrupts on an idle core:
    
    <idle>-0     [010]  3900.671297: timer_interrupt_entry: pt_regs=c0000000ce1e7b10
    <idle>-0     [010]  3900.671302: timer_interrupt_exit: pt_regs=c0000000ce1e7b10
    
    <idle>-0     [010]  3911.042963: timer_interrupt_entry: pt_regs=c0000000ce1e7b10
    <idle>-0     [010]  3911.042968: timer_interrupt_exit: pt_regs=c0000000ce1e7b10
    
    <idle>-0     [010]  3921.414630: timer_interrupt_entry: pt_regs=c0000000ce1e7b10
    <idle>-0     [010]  3921.414635: timer_interrupt_exit: pt_regs=c0000000ce1e7b10
    
    Since we have a 207MHz decrementer it will go negative and fire every 10.37s
    even if Linux is completely idle.
    Signed-off-by: default avatarAnton Blanchard <anton@samba.org>
    Signed-off-by: default avatarPaul Mackerras <paulus@samba.org>
    6795b85c
trace.h 1.26 KB