On 12/12/18 7:53 PM, Michael S. Tsirkin wrote:
On Wed, Dec 12, 2018 at 05:34:31PM +0100, Maxime Coquelin wrote:
Hi Ilya,
On 12/12/18 4:23 PM, Ilya Maximets wrote:
On 12.12.2018 11:24, Maxime Coquelin wrote:
Instead of writing back descriptors chains in order, let's
write the first chain flags last in order to improve batching.
With Kernel's pktgen benchmark, ~3% performance gain is measured.
Signed-off-by: Maxime Coquelin <maxime.coque...@redhat.com>
---
lib/librte_vhost/virtio_net.c | 39 +++++++++++++++++++++--------------
1 file changed, 24 insertions(+), 15 deletions(-)
Hi.
I made some rough testing on my ARMv8 system with this patch and v1 of it.
Here is the performance difference with current master:
v1: +1.1 %
v2: -3.6 %
So, write barriers are quiet heavy in practice.
Thanks for testing it on ARM. Indeed, SMP WMB is heavier on ARM.
Besides your ideas for improving packed rings, maybe we should switch to
load_acquite/store_release?
See
virtio: use smp_load_acquire/smp_store_release
which worked fine but as I only tested on x86 did not result in any gains.
Thanks for the pointer.
We'll look into it for v19.05, as -rc1 for v19.02 is planned for end of
week, so it will be too late to introduce such changes.
Regards,
Maxime
