linux

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Rusty Russell 7b21e34fd1 virtio: harsher barriers for rpmsg. We were cheating with our barriers; using the smp ones rather than the real device ones. That was fine, until rpmsg came along, which is used to talk to a real device (a non-SMP CPU). Unfortunately, just putting back the real barriers (reverting `d57ed95d`) causes a performance regression on virtio-pci. In particular, Amos reports netbench's TCP_RR over virtio_net CPU utilization increased up to 35% while throughput went down by up to 14%. By comparison, this branch is in the noise. Reference: https://lkml.org/lkml/2011/12/11/22 Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>	2012-01-12 15:44:42 +10:30
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Makefile	…
kvm_virtio.c	virtio: harsher barriers for rpmsg.	2012-01-12 15:44:42 +10:30

Rusty Russell 7b21e34fd1 virtio: harsher barriers for rpmsg.

We were cheating with our barriers; using the smp ones rather than the
real device ones.  That was fine, until rpmsg came along, which is
used to talk to a real device (a non-SMP CPU).

Unfortunately, just putting back the real barriers (reverting
d57ed95d) causes a performance regression on virtio-pci.  In
particular, Amos reports netbench's TCP_RR over virtio_net CPU
utilization increased up to 35% while throughput went down by up to
14%.

By comparison, this branch is in the noise.

Reference: https://lkml.org/lkml/2011/12/11/22

Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>

2012-01-12 15:44:42 +10:30

Makefile

…

kvm_virtio.c virtio: harsher barriers for rpmsg. 2012-01-12 15:44:42 +10:30