Re: [PATCH RFC 01/11] net/mlx5e: Single flow order-0 pages for Striding RQ

Hi Alexei,

On 07/09/2016 8:31 PM, Alexei Starovoitov wrote:

On Wed, Sep 07, 2016 at 03:42:22PM +0300, Saeed Mahameed wrote:

quoted

From: Tariq Toukan <tariqt-VPRAkNaXOzVWk0Htik3J/w@public.gmane.org>

To improve the memory consumption scheme, we omit the flow that
demands and splits high-order pages in Striding RQ, and stay
with a single Striding RQ flow that uses order-0 pages.

Moving to fragmented memory allows the use of larger MPWQEs,
which reduces the number of UMR posts and filler CQEs.

Moving to a single flow allows several optimizations that improve
performance, especially in production servers where we would
anyway fallback to order-0 allocations:
- inline functions that were called via function pointers.
- improve the UMR post process.

This patch alone is expected to give a slight performance reduction.
However, the new memory scheme gives the possibility to use a page-cache
of a fair size, that doesn't inflate the memory footprint, which will
dramatically fix the reduction and even give a huge gain.

We ran pktgen single-stream benchmarks, with iptables-raw-drop:

Single stride, 64 bytes:
* 4,739,057 - baseline
* 4,749,550 - this patch
no reduction

Larger packets, no page cross, 1024 bytes:
* 3,982,361 - baseline
* 3,845,682 - this patch
3.5% reduction

Larger packets, every 3rd packet crosses a page, 1500 bytes:
* 3,731,189 - baseline
* 3,579,414 - this patch
4% reduction

imo it's not a realistic use case, but would be good to mention that
patch 3 brings performance back for this use case anyway.

Exactly, that's what I meant in the previous paragraph (".. will dramatically fix the reduction and even give a huge gain.")
Regards,
Tariq