Commit 083d012a authored by Richard Henderson's avatar Richard Henderson Committed by Paolo Bonzini
Browse files

cutils: Add generic prefetch 



There's no real knowledge of the cacheline size,
just prefetching one loop ahead.

Signed-off-by: default avatarRichard Henderson <rth@twiddle.net>
Message-Id: <1472496380-19706-7-git-send-email-rth@twiddle.net>
Signed-off-by: default avatarPaolo Bonzini <pbonzini@redhat.com>
parent 86444f08

util/bufferiszero.c

+5 −0
Original line number Diff line number Diff line
@@ -38,6 +38,8 @@ static bool NAME(const void *buf, size_t len) \ 
    do {                                                        \

        const VECTYPE *p = buf;                                 \

        VECTYPE t;                                              \

        __builtin_prefetch(buf + SIZE);                         \

        barrier();                                              \

        if (SIZE == sizeof(VECTYPE) * 4) {                      \

            t = (p[0] | p[1]) | (p[2] | p[3]);                  \

        } else if (SIZE == sizeof(VECTYPE) * 8) {               \
@@ -219,6 +221,9 @@ bool buffer_is_zero(const void *buf, size_t len) 
        return true;

    }



    /* Fetch the beginning of the buffer while we select the accelerator.  */

    __builtin_prefetch(buf);



    /* Use an optimized zero check if possible.  Note that this also

       includes a check for an unrolled loop over 64-bit integers.  */

    return select_accel_fn(buf, len);