• Anton Blanchard's avatar
    powerpc: tracing: Add hypervisor call tracepoints · c8cd093a
    Anton Blanchard authored
    Add hcall_entry and hcall_exit tracepoints.  This replaces the inline
    assembly HCALL_STATS code and converts it to use the new tracepoints.
    
    To keep the disabled case as quick as possible, we embed a status word
    in the TOC so we can get at it with a single load.  By doing so we
    keep the overhead at a minimum.  Time taken for a null hcall:
    
    No tracepoint code:	135.79 cycles
    Disabled tracepoints:	137.95 cycles
    
    For reference, before this patch enabling HCALL_STATS resulted in a null
    hcall of 201.44 cycles!
    Signed-off-by: default avatarAnton Blanchard <anton@samba.org>
    Signed-off-by: default avatarPaul Mackerras <paulus@samba.org>
    c8cd093a
trace.h 2.06 KB