From: David Vrabel <david.vrabel@citrix.com>
To: Jan Beulich <JBeulich@suse.com>
Cc: <xen-devel@lists.xenproject.org>,
Boris Ostrovsky <boris.ostrovsky@oracle.com>,
<netdev@vger.kernel.org>
Subject: Re: [Xen-devel] [PATCHv1] xen-netfront: always keep the Rx ring full of requests
Date: Thu, 2 Oct 2014 14:55:47 +0100 [thread overview]
Message-ID: <542D5963.10104@citrix.com> (raw)
In-Reply-To: <542D7361020000780003C014@mail.emea.novell.com>
On 02/10/14 14:46, Jan Beulich wrote:
>>>> On 02.10.14 at 15:33, <david.vrabel@citrix.com> 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.
>
> The performance benefits are nice, but does the above statement
> scale to hundreds of guests with perhaps multiple NICs and/or
> queues?
Yes, because:
a) Even the full 1 MiB is a tiny fraction of a typically modern Linux VM
(for example, the AWS micro instance still has 1 GiB of memory).
b) Netfront would have used up to 1 MiB already even with moderate data
rates (there was no adjustment of target based on memory pressure).
c) Small VMs are going to typically have one VCPU and hence only one queue.
David
next prev parent reply other threads:[~2014-10-02 13:55 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 [this message]
2014-10-03 22:54 ` David Miller
2014-10-06 15:35 ` [Xen-devel] " annie li
2014-10-06 16:00 ` 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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