linux-kernel - Re: [PATCH] vhost: Add polling mode

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Message-ID: <OF93E480CE.EFA0854D-ONC2257D32.003BE092-C2257D32.003C1F49@il.ibm.com>
Date:	Tue, 12 Aug 2014 13:57:05 +0300
From:	Razya Ladelsky <razya@...ibm.com>
To:	"Michael S. Tsirkin" <mst@...hat.com>
Cc:	abel.gordon@...il.com, Alex Glikson <GLIKSON@...ibm.com>,
	David Miller <davem@...emloft.net>,
	Eran Raichstein <ERANRA@...ibm.com>,
	Joel Nider <JOELN@...ibm.com>, kvm@...r.kernel.org,
	linux-kernel@...r.kernel.org, netdev@...r.kernel.org,
	virtualization@...ts.linux-foundation.org,
	Yossi Kuperman1 <YOSSIKU@...ibm.com>
Subject: Re: [PATCH] vhost: Add polling mode

"Michael S. Tsirkin" <mst@...hat.com> wrote on 12/08/2014 12:18:50 PM:

> From: "Michael S. Tsirkin" <mst@...hat.com>
> To: David Miller <davem@...emloft.net>
> Cc: Razya Ladelsky/Haifa/IBM@...IL, kvm@...r.kernel.org, Alex 
> Glikson/Haifa/IBM@...IL, Eran Raichstein/Haifa/IBM@...IL, Yossi 
> Kuperman1/Haifa/IBM@...IL, Joel Nider/Haifa/IBM@...IL, 
> abel.gordon@...il.com, linux-kernel@...r.kernel.org, 
> netdev@...r.kernel.org, virtualization@...ts.linux-foundation.org
> Date: 12/08/2014 12:18 PM
> Subject: Re: [PATCH] vhost: Add polling mode
> 
> On Mon, Aug 11, 2014 at 12:46:21PM -0700, David Miller wrote:
> > From: "Michael S. Tsirkin" <mst@...hat.com>
> > Date: Sun, 10 Aug 2014 21:45:59 +0200
> > 
> > > On Sun, Aug 10, 2014 at 11:30:35AM +0300, Razya Ladelsky wrote:
> >  ...
> > > And, did your tests actually produce 100% load on both host CPUs?
> >  ...
> > 
> > Michael, please do not quote an entire patch just to ask a one line
> > question.
> > 
> > I truly, truly, wish it was simpler in modern email clients to delete
> > the unrelated quoted material because I bet when people do this they
> > are simply being lazy.
> > 
> > Thank you.
> 
> Lazy - mea culpa, though I'm using mutt so it isn't even hard.
> 
> The question still stands: the test results are only valid
> if CPU was at 100% in all configurations.
> This is the reason I generally prefer it when people report
> throughput divided by CPU (power would be good too but it still
> isn't easy for people to get that number).
> 

Hi Michael,

Sorry for the delay, had some problems with my mailbox, and I realized 
just now that 
my reply wasn't sent.
The vm indeed ALWAYS utilized 100% cpu, whether polling was enabled or 
not.
The vhost thread utilized less than 100% (of the other cpu) when polling 
was disabled.
Enabling polling increased its utilization to 100% (in which case both 
cpus were 100% utilized). 


> -- 
> MST
> 

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