[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]
Re: [Xen-devel] Slow guest network I/O when CPU is pegged - Looking for acknowledgement from developers
- To: "Pasi Kärkkäinen" <pasik@xxxxxx>
- From: "Anand Gupta" <xen.mails@xxxxxxxxx>
- Date: Thu, 20 Apr 2006 01:16:39 +0530
- Cc: Matt Ayres <matta@xxxxxxxxxxxx>, "xen-devel@xxxxxxxxxxxxxxxxxxx" <xen-devel@xxxxxxxxxxxxxxxxxxx>
- Delivery-date: Wed, 19 Apr 2006 12:46:59 -0700
- Domainkey-signature: a=rsa-sha1; q=dns; c=nofws; s=beta; d=gmail.com; h=received:message-id:date:from:to:subject:cc:in-reply-to:mime-version:content-type:references; b=k6MhKGrAsIGNBi6D9vJLRDUtDQFzNNa+DnZ5Q5OT2qrlWQrJGQIDd3sbFYZu/jsvUZuv0kQNpJmonMHcKF4g3rbw2toidSofhWD4CEpMmaDXoQOVEFnyOpIzMET5fgK8ySLXBCi8o4MtQfBUR7f9EIOPSk/TiM8fRScqZV081Lc=
- List-id: Xen developer discussion <xen-devel.lists.xensource.com>
How does one change from SEDF -> BVT ?
On 4/19/06, Pasi Kärkkäinen <pasik@xxxxxx> wrote:
On Thu, Apr 13, 2006 at 09:52:19AM -0400, Matt Ayres wrote: > > > Keir Fraser wrote: > > > >On 7 Apr 2006, at 19:25, Matt Ayres wrote: > > > >>Ok, so we all know that guest network I/O is slow when the system
> >>CPU's are being utilized extensively whether it be from dom0 or from > >>other guests. Lots of people have written about this and I can post > >>concrete tests if required. > >>
> >>I'm just looking for one of the Xen developers to acknowledge that > >>they have been able to replicate the problem and it is indeed being > >>worked on or will be sometime in the near future. No one has
> >>acknowledged any of the previous threads on either list so I want to > >>make sure it is an outstanding issue that is not being overlooked. > > > >It depends on the setup but poor scheduling is the main reason for poor
> >network performance, usually. SEDF seems to have some problems with > >real-time domains (like domain0 with its default scheduling parameters) > >and gives them all the CPU they want -- this is obviously going to be
> >bad if a client domain is scheduled on the same CPU. > > You hit it right here. I did some thinking and informal tests and came > to a conclusion. The SEDF is the "new kid" on the block and it also the
> default, hence everyone is using it. In many cases (such as mine) > people are just using SEDF with the weight. Also, extratime seems to be > broken (according to Stephen in an old post) and doesn't work well with
> heavy I/O. It especially doesn't do well when dom0 does anything else > but provide block and network device access, even when it is tuned in > proportion to the other VM weights. > > Another argument is that the SEDF scheduler is just TOO good at what it
> does, in that case it needs some work done to be more flexible. Users > should consider and test both schedulers before making a decision on > which to use, there is no clear "winner". >
> Why am I replying? I did my tests. BVT is nowhere near as strict as > SEDF in it's "while 1" tests as far as allocating CPU to domains, but it > seems to do a good enough job of providing a proportional share based on
> weight (duh) in a real world production environment. It also fixed my > network throughput problem. > > Thanks, > Matt >
It seems BVT was the recommended CPU scheduler in Xen 2. I think I'll have
to try it too.. I hope it will fix the network throughput problems I'm seeing in Xen 3.
Are there any downsides in using BVT scheduler in Xen 3.0 ? Why was the default changed from BVT -> SEDF ?
-- Pasi
_______________________________________________ Xen-devel mailing list Xen-devel@xxxxxxxxxxxxxxxxxxx
http://lists.xensource.com/xen-devel
-- regards,
Anand Gupta
_______________________________________________
Xen-devel mailing list
Xen-devel@xxxxxxxxxxxxxxxxxxx
http://lists.xensource.com/xen-devel
|