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[0/3] vhost: make virtqueue cache-friendly

Message ID 20201222135658.53916-1-maxime.coquelin@redhat.com (mailing list archive)
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Series vhost: make virtqueue cache-friendly | expand

Message

Maxime Coquelin Dec. 22, 2020, 1:56 p.m. UTC
As done for Virtio PMD, this series improves cache utilization
of the vhost_virtqueue struct by removing unused field,
make the live-migration cache dynamically allocated at
live-migration setup time and by moving fields
around so that hot fields are on the first cachelines.

With this series, The struct vhost_virtqueue size goes
from 832B (13 cachelines) down to 320B (5 cachelines).

With this series and the virtio one, I measure a gain
of up to 8% in IO loop micro-benchmark with packed
ring, and 5% with split ring.

I don't have a setup at hand to run PVP testing, but
it might be interresting to get the numbers as I
suspect the cache pressure is higher in this test as
in real use-cases.

Maxime Coquelin (3):
  vhost: remove unused Vhost virtqueue field
  vhost: move dirty logging cache out of the virtqueue
  vhost: optimize vhost virtqueue struct

 lib/librte_vhost/vhost.c      | 14 +++++++--
 lib/librte_vhost/vhost.h      | 54 +++++++++++++++++------------------
 lib/librte_vhost/vhost_user.c | 25 ++++++++++++++++
 3 files changed, 64 insertions(+), 29 deletions(-)

Comments

Maxime Coquelin Jan. 25, 2021, 5:30 p.m. UTC | #1
On 12/22/20 2:56 PM, Maxime Coquelin wrote:
> As done for Virtio PMD, this series improves cache utilization
> of the vhost_virtqueue struct by removing unused field,
> make the live-migration cache dynamically allocated at
> live-migration setup time and by moving fields
> around so that hot fields are on the first cachelines.
> 
> With this series, The struct vhost_virtqueue size goes
> from 832B (13 cachelines) down to 320B (5 cachelines).
> 
> With this series and the virtio one, I measure a gain
> of up to 8% in IO loop micro-benchmark with packed
> ring, and 5% with split ring.
> 
> I don't have a setup at hand to run PVP testing, but
> it might be interresting to get the numbers as I
> suspect the cache pressure is higher in this test as
> in real use-cases.
> 
> Maxime Coquelin (3):
>   vhost: remove unused Vhost virtqueue field
>   vhost: move dirty logging cache out of the virtqueue
>   vhost: optimize vhost virtqueue struct
> 
>  lib/librte_vhost/vhost.c      | 14 +++++++--
>  lib/librte_vhost/vhost.h      | 54 +++++++++++++++++------------------
>  lib/librte_vhost/vhost_user.c | 25 ++++++++++++++++
>  3 files changed, 64 insertions(+), 29 deletions(-)
> 
Deferring to v21.05 release.

Maxime