[dpdk-dev] [PATCH v2 1/1] doc: correct Vhost Sample Application guide

Iremonger, Bernard bernard.iremonger at intel.com
Thu Dec 10 10:58:40 CET 2015


Hi Yuanhan,

> -----Original Message-----
> From: Yuanhan Liu [mailto:yuanhan.liu at linux.intel.com]
> Sent: Thursday, December 10, 2015 6:53 AM
> To: Iremonger, Bernard <bernard.iremonger at intel.com>
> Cc: dev at dpdk.org
> Subject: Re: [dpdk-dev] [PATCH v2 1/1] doc: correct Vhost Sample
> Application guide
> 
> On Wed, Dec 09, 2015 at 05:18:38PM +0000, Bernard Iremonger wrote:
> > correct sample console commands
> 
> You'd state what exactly this patch corrects here, and why is that needed.

I will add more information to the commit message.

 
> >
> > changes in v2:
> > remove "user at target:~$" prefixes in command lines.
> > use continuation character to stay within 80 character limit.
> > wrap sample python code.
> >
> > Fixes: d0dff9ba445e ("doc: sample application user guide"
> > Fixes: 9bc23cb8209c ("doc: add vhost-user to sample guide")
> > Fixes: 43866bf71d58 ("doc: fix vhost sample parameter")
> > Signed-off-by: Bernard Iremonger <bernard.iremonger at intel.com>
> > ---
> ...
> >
> > @@ -386,13 +386,15 @@ Running the Sample Code
> >
> >      .. code-block:: console
> >
> > -        user at target:~$ ./build/app/vhost-switch -c f -n 4 --huge-dir /
> mnt/huge -- -p 0x1 --dev-basename usvhost
> > +        ./vhost-switch -c f -n 4 --socket-mem 1024 --huge-dir /mnt/huge \
> > +         -- -p 0x1 --dev-basename usvhost
> 
> I don't think that's a right "correction": vhost-swtich would fail to
> start:
> 
>     EAL: Error - exiting with code: 1
>     Cause: Cannot create mbuf pool
> 
> As vhost-switch creates more mbuf than 1024M can hold.
> 
> However, I do think that adding this option is necessary, otherwise, all
> hugepages will be allocated to vhost-switch, leaving no memory for starting
> VM at all. (And this is kind of informatin you need to put into commit log).
> 
> And limiting it to "1024M" is reasonable as well, so that we can run it on a
> desktop (or laptop) without too many memories. You just need fix vhost-
> switch example to not allocate too many mbufs by default.
> 
> 	--yliu

Yes the --socket-mem  <number> option is necessary.  
I will add a note that a value of  <number> may need to be greater than 1024.
I will submit a patch to vhost-switch to reduce the number of mbufs.

Regards,

Bernard.



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