"Michael S. Tsirkin" <mst@xxxxxxxxxx> writes: >> Without the inline keywords, it doesn't inline virtqueue_add, and thus >> sg_next_chained and sg_next_add aren't inlined: >> >> $ for i in `seq 50`; do /usr/bin/time --format=%U ./vringh_test --indirect --eventidx --parallel; done 2>&1 | stats --trim-outliers >> Using CPUS 0 and 3 >> Guest: notified 39102-39145(39105), pinged 39060-39063(39063) >> Host: notified 39060-39063(39063), pinged 19551-19581(19553) >> 3.050000-3.220000(3.136875) >> >> With inline: >> >> $ for i in `seq 50`; do /usr/bin/time --format=%U ./vringh_test --indirect --eventidx --parallel; done 2>&1 | stats --trim-outliers >> Using CPUS 0 and 3 >> Guest: notified 39084-39148(39099), pinged 39062-39063(39062) >> Host: notified 39062-39063(39062), pinged 19542-19574(19550) >> 2.940000-3.140000(3.014583) >> >> Cheers, >> Rusty. > > Cool and did it actually unroll all loops? Sorry for the delay in answering... I spent a day chasing red-herrings, as my tests became limited by the vringh side, so optimizations on the virtio side were having no effect :( I'll answer a related question based on the current tree, where virtio_add_outbuf (and virtio_add_inbuf) are the stars: return virtqueue_add(vq, &sg, sg_next_arr, num, 0, 1, 0, data, gfp); Ideally, gcc would eliminated the input-descriptor loop altogether (that 0 for in_sgs), and unroll the 1-iteration output-descriptor loop into straightline code. Which it seems to have done, by my reading of the asm (at least, for gcc 4.7 on 32-bit x86). Cheers, Rusty. _______________________________________________ Virtualization mailing list Virtualization@xxxxxxxxxxxxxxxxxxxxxxxxxx https://lists.linuxfoundation.org/mailman/listinfo/virtualization
