From: annie li <annie.li@oracle•com>
To: David Vrabel <david.vrabel@citrix•com>
Cc: netdev@vger•kernel.org, xen-devel@lists•xenproject.org,
Boris Ostrovsky <boris.ostrovsky@oracle•com>
Subject: Re: [Xen-devel] [PATCHv1] xen-netfront: always keep the Rx ring full of requests
Date: Mon, 06 Oct 2014 11:35:46 -0400 [thread overview]
Message-ID: <5432B6D2.9030503@oracle.com> (raw)
In-Reply-To: <1412256826-18874-1-git-send-email-david.vrabel@citrix.com>
On 2014/10/2 9:33, David Vrabel wrote:
> A full Rx ring only requires 1 MiB of memory. This is not enough
> memory that it is useful to dynamically scale the number of Rx
> requests in the ring based on traffic rates.
>
> Keeping the ring full of Rx requests handles bursty traffic better
> than trying to converges on an optimal number of requests to keep
> filled.
>
> On a 4 core host, an iperf -P 64 -t 60 run from dom0 to a 4 VCPU guest
> improved from 5.1 Gbit/s to 5.6 Gbit/s. Gains with more bursty
> traffic are expected to be higher.
Although removing sysfs is connected with the code change for full Rx
ring utilization, I assume it is better to split this patch into two to
make it simpler?
...snip...
>
> + queue->rx.req_prod_pvt = req_prod;
> +
> + /* Not enough requests? Try again later. */
> + if (req_prod - queue->rx.rsp_cons < NET_RX_SLOTS_MIN) {
> + mod_timer(&queue->rx_refill_timer, jiffies + (HZ/10));
> + return;
If the previous for loop breaks because of failure of
xennet_alloc_one_rx_buffer, then notify_remote_via_irq is missed here if
the code returns directly.
Thanks
Annie
> + }
> +
next prev parent reply other threads:[~2014-10-06 15:35 UTC|newest]
Thread overview: 10+ messages / expand[flat|nested] mbox.gz Atom feed top
2014-10-02 13:33 [PATCHv1] xen-netfront: always keep the Rx ring full of requests David Vrabel
2014-10-02 13:46 ` [Xen-devel] " Jan Beulich
2014-10-02 13:55 ` David Vrabel
2014-10-03 22:54 ` David Miller
2014-10-06 15:35 ` annie li [this message]
2014-10-06 16:00 ` [Xen-devel] " David Vrabel
2014-10-06 18:41 ` annie li
2014-10-06 21:07 ` David Miller
2014-10-07 9:43 ` David Vrabel
2014-10-07 13:12 ` annie li
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