Hi,
Anton Blanchard wrote:
Is a conditional cheaper than a divide? In case of a misprediction I
would assume it to be significantly slower and I don't know the ratio
of mispredictions for this branch.
A quick scan of the web shows 40 cycles for athlon64 idiv, and its
similarly slow on many other cpus. Even assuming you mispredict every
branch its going to be a win.
Anton
as our queue size is always a power of 2, we simply use:
i++;
i &= (ringbufferlength - 1)
So we can get along without the if.
Jan-Bernd
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