Alexander Duyck <alexander.h.duyck@xxxxxxxxx> writes: > While working on 10Gb/s routing performance I found a significant amount of > time was being spent in the swiotlb DMA handler. Further digging found that a > significant amount of this was due to the fact that virtual to physical > address translation and calling the function that did it. It accounted for > nearly 60% of the total overhead. Can you find out why that is? Traditionally virt_to_phys was just a subtraction. Then later on it was a if and a subtraction. It cannot really be that expensive. Do you have some debugging enabled? Really virt_to_phys should be fixed. Such fundamental operations shouldn't slow. I don't think hacking up all the users to work around this is the r ight way. Looking at the code a bit someone (crazy) made it out of line. But that cannot explain that much overhead. -Andi -- ak@xxxxxxxxxxxxxxx -- Speaking for myself only _______________________________________________ devel mailing list devel@xxxxxxxxxxxxxxxxxxxxxx http://driverdev.linuxdriverproject.org/mailman/listinfo/devel
