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

On Fri, Sep 08, 2017 at 03:41:08PM +0800, Yuanhan Liu wrote:

On Thu, Aug 24, 2017 at 10:19:39AM +0800, 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.

The number showed in other replies looks really impressive. Great work!
This patch also looks good to me. I have one minor comment though.

[...]

quoted

+/*
+ * Structure contains the info for each batched memory copy.
+ */
+struct burst_copy_elem {
+	void *dst;
+	void *src;
+	uint32_t len;
+	uint64_t log_addr;
+};

Like the title says, it's more about batch (but not burst). Also, it's
not a good idea to mix burst and batch. I'd suggest you to use the term
"batch" consistently.

Okay, I'll change it. Thank you! :-)

Best regards,
Tiwei Bie