Re: [PATCH v2] vhost: adaptively batch small guest memory copies

On Sat, Sep 09, 2017 at 08:28:57PM +0530, santosh wrote:

On Friday 08 September 2017 06:20 PM, Tiwei Bie wrote:

quoted

This patch adaptively batches the small guest memory copies.
By batching the small copies, the efficiency of executing the
memory LOAD instructions can be improved greatly, because the
memory LOAD latency can be effectively hidden by the pipeline.
We saw great performance boosts for small packets PVP test.

This patch improves the performance for small packets, and has
distinguished the packets by size. So although the performance
for big packets doesn't change, it makes it relatively easy to
do some special optimizations for the big packets too.

Signed-off-by: Tiwei Bie <redacted>
Signed-off-by: Zhihong Wang <redacted>
Signed-off-by: Zhiyong Yang <redacted>
Reviewed-by: Maxime Coquelin <redacted>
---
This optimization depends on the CPU internal pipeline design.
So further tests (e.g. ARM) from the community is appreciated.

v2: s/burst_copy/batch_copy/g

In pvp setup for arm64 platform, no performance drop noticed with this patch but no significant performance gain either. Tested-by: Santosh Shukla [off-list ref]

Thank you very much for testing this patch!

Best regards,
Tiwei Bie