DPDK patches and discussions
 help / color / mirror / Atom feed
From: Stephen Hemminger <stephen@networkplumber.org>
To: Ciara Loftus <ciara.loftus@intel.com>
Cc: dev@dpdk.org, xiaolong.ye@intel.com, magnus.karlsson@intel.com
Subject: Re: [dpdk-dev] [PATCH] net/af_xdp: optimisations to improve packet loss
Date: Tue, 16 Jun 2020 20:42:16 -0700
Message-ID: <20200616204216.35e362b3@hermes.lan> (raw)
In-Reply-To: <20200612141746.9450-1-ciara.loftus@intel.com>

On Fri, 12 Jun 2020 14:17:46 +0000
Ciara Loftus <ciara.loftus@intel.com> wrote:

> This commit makes some changes to the AF_XDP PMD in an effort to improve
> its packet loss characteristics.
> 1. In the case of failed transmission due to inability to reserve a tx
> descriptor, the PMD now pulls from the completion ring, issues a syscall
> in which the kernel attempts to complete outstanding tx operations, then
> tries to reserve the tx descriptor again. Prior to this we dropped the
> packet after the syscall and didn't try to re-reserve.
> 2. During completion ring cleanup, always pull as many entries as possible
> from the ring as opposed to the batch size or just how many packets
> we're going to attempt to send. Keeping the completion ring emptier should
> reduce failed transmissions in the kernel, as the kernel requires space in
> the completion ring to successfully tx.
> 3. Size the fill ring as twice the receive ring size which may help reduce
> allocation failures in the driver.
> With these changes, a benchmark which measured the packet rate at which
> 0.01% packet loss could be reached improved from ~0.1G to ~3Gbps.
> Signed-off-by: Ciara Loftus <ciara.loftus@intel.com>

You might want to add the ability to emulate a tx_free threshold
by pulling more completions earlier.

  parent reply	other threads:[~2020-06-17  3:42 UTC|newest]

Thread overview: 4+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-06-12 14:17 Ciara Loftus
2020-06-17  2:34 ` Ye Xiaolong
2020-06-17  3:42 ` Stephen Hemminger [this message]
2020-06-23 14:50   ` Loftus, Ciara

Reply instructions:

You may reply publicly to this message via plain-text email
using any one of the following methods:

* Save the following mbox file, import it into your mail client,
  and reply-to-all from there: mbox

  Avoid top-posting and favor interleaved quoting:

* Reply using the --to, --cc, and --in-reply-to
  switches of git-send-email(1):

  git send-email \
    --in-reply-to=20200616204216.35e362b3@hermes.lan \
    --to=stephen@networkplumber.org \
    --cc=ciara.loftus@intel.com \
    --cc=dev@dpdk.org \
    --cc=magnus.karlsson@intel.com \
    --cc=xiaolong.ye@intel.com \


* If your mail client supports setting the In-Reply-To header
  via mailto: links, try the mailto: link

DPDK patches and discussions

This inbox may be cloned and mirrored by anyone:

	git clone --mirror https://inbox.dpdk.org/dev/0 dev/git/0.git

	# If you have public-inbox 1.1+ installed, you may
	# initialize and index your mirror using the following commands:
	public-inbox-init -V2 dev dev/ https://inbox.dpdk.org/dev \
	public-inbox-index dev

Example config snippet for mirrors.
Newsgroup available over NNTP:

AGPL code for this site: git clone https://public-inbox.org/public-inbox.git