• Adhemerval Zanella's avatar
    powerpc: Add VDSO version of time · fcb41a20
    Adhemerval Zanella authored
    On 04/18/2013 07:38 PM, Anton Blanchard wrote:
    > Since you are only reading one long you shouldn't need to check the
    > update count and loop, you will always see a consistent value. The
    > system call version of time() just does an unprotected load for example.
    
    Fixed.
    
    > With the above change and with Michael's comments covered (decent
    > changelog entry and Signed-off-by):
    >
    > Acked-by: Anton Blanchard <anton@samba.org>
    
    Thanks for the review, below the updated patch:
    
    From: Adhemerval Zanella <azanella@linux.vnet.ibm.com>
    
    This patch implement the time syscall as vDSO. The performance speedups
    are:
    
    Baseline PPC32: 380 nsec
    Baseline PPC64: 350 nsec
    vdso PPC32:      20 nsec
    vsdo PPC64:      20 nsec
    
    Tested on 64 bit build with both 32 bit and 64 bit userland.
    Acked-by: default avatarAnton Blanchard <anton@samba.org>
    Signed-off-by: default avatarAdhemerval Zanella <azanella@linux.vnet.ibm.com>
    Signed-off-by: default avatarBenjamin Herrenschmidt <benh@kernel.crashing.org>
    fcb41a20
gettimeofday.S 6.81 KB