Il 07/09/2014 12:32, Ming Lei ha scritto: > It is a good idea to disable SG merge for vq incapable of indirect because > there are very limited direct descriptors.
I think you mean _enabling_ SG merge if indirect descriptors are not there. > For vq capable of indirect, it should be better to not do SG merge at default > because: > > - from hypervisor view, no matter how many segments one req has, all are > submitted to host kernel by one syscall, such as readv/io_submit > > - host kernel still need to do the same merge again Here we agree. Paolo > From my test(virtio-blk over null_blk), looks enabling SG merge may cause > throughput a little drop(~3%). -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [email protected] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
