• Anton Blanchard's avatar
    powerpc/time: Optimise decrementer_check_overflow · 7df10275
    Anton Blanchard authored
    decrementer_check_overflow is called from arch_local_irq_restore so
    we want to make it as light weight as possible. As such, turn
    decrementer_check_overflow into an inline function.
    
    To avoid a circular mess of includes, separate out the two components
    of struct decrementer_clock and keep the struct clock_event_device
    part local to time.c.
    
    The fast path improves from:
    
    arch_local_irq_restore
         0:       mflr    r0
         4:       std     r0,16(r1)
         8:       stdu    r1,-112(r1)
         c:       stb     r3,578(r13)
        10:       cmpdi   cr7,r3,0
        14:       beq-    cr7,24 <.arch_local_irq_restore+0x24>
    ...
        24:       addi    r1,r1,112
        28:       ld      r0,16(r1)
        2c:       mtlr    r0
        30:       blr
    
    to:
    
    arch_local_irq_restore
        0:       std     r30,-16(r1)
        4:       ld      r30,0(r2)
        8:       stb     r3,578(r13)
        c:       cmpdi   cr7,r3,0
       10:       beq-    cr7,6c <.arch_local_irq_restore+0x6c>
    ...
       6c:       ld      r30,-16(r1)
       70:       blr
    
    Unfortunately we still setup a local TOC (due to -mminimal-toc). Yet
    another sign we should be moving to -mcmodel=medium.
    Signed-off-by: default avatarAnton Blanchard <anton@samba.org>
    Signed-off-by: default avatarBenjamin Herrenschmidt <benh@kernel.crashing.org>
    7df10275
time.h 5.13 KB