On Thu, May 29, 2014 at 08:38:33PM +0930, Rusty Russell wrote: > Minchan Kim <minchan@xxxxxxxxxx> writes: > > Hello Rusty, > > > > On Thu, May 29, 2014 at 04:56:41PM +0930, Rusty Russell wrote: > >> They don't make much difference: the easier fix is use gcc 4.8 > >> which drops stack required across virtio block's virtio_queue_rq > >> down to that kmalloc in virtio_ring from 528 to 392 bytes. > >> > >> Still, these (*lightly tested*) patches reduce to 432 bytes, > >> even for gcc 4.6.4. Posted here FYI. > > > > I am testing with below which was hack for Dave's idea so don't have > > a machine to test your patches until tomorrow. > > So, I will queue your patches into testing machine tomorrow morning. > > More interesting would be updating your compiler to 4.8, I think. > Saving <100 bytes on virtio is not going to save you, right? But in my report, virtio_ring consumes more than yours. As I mentioned other thread to Steven, I don't know why stacktrace report vring_add_indirect consumes 376-byte. Apparently, objdump says it didn't consume too much so I'd like to test your patches and see the result. Thanks. [ 1065.604404] kworker/-5766 0d..2 1071625993us : stack_trace_call: 10) 6376 376 vring_add_indirect+0x36/0x200 [ 1065.604404] kworker/-5766 0d..2 1071625993us : stack_trace_call: 11) 6000 144 virtqueue_add_sgs+0x2e2/0x320 [ 1065.604404] kworker/-5766 0d..2 1071625993us : stack_trace_call: 12) 5856 288 __virtblk_add_req+0xda/0x1b0 [ 1065.604404] kworker/-5766 0d..2 1071625993us : stack_trace_call: 13) 5568 96 virtio_queue_rq+0xd3/0x1d0 > > Cheers, > Rusty. > > -- > To unsubscribe, send a message with 'unsubscribe linux-mm' in > the body to majordomo@xxxxxxxxx. For more info on Linux MM, > see: http://www.linux-mm.org/ . > Don't email: <a href=mailto:"dont@xxxxxxxxx";> email@xxxxxxxxx </a> -- Kind regards, Minchan Kim -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@xxxxxxxxx. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: <a href=mailto:"dont@xxxxxxxxx";> email@xxxxxxxxx </a>