On Thu, 2014-06-26 at 16:53 +0200, Bart Van Assche wrote: > On 06/11/14 11:09, Sagi Grimberg wrote: > > + return xfer_len + (xfer_len >> ilog2(sector_size)) * 8; > > Sorry that I just noticed this now, but why is a shift-right and ilog2() > used in the above expression instead of just dividing the transfer > length by the sector size ? It's a performance thing. Division is really slow on most CPUs. However, we know the divisor is a power of two so we re-express the division as a shift, which the processor can do really fast. James -- To unsubscribe from this list: send the line "unsubscribe linux-scsi" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
