Load increase= after memory upgrade (part2)

From mboxrd@z Thu Jan 1 00:00:00 1970 From: =?utf-8?Q?Carsten_Schiers?= Subject: Load increase after memory upgrade (part2) Date: Thu, 24 Nov 2011 13:28:44 +0100 Message-ID: Mime-Version: 1.0 Content-Type: multipart/mixed; boundary="===============5279143288043207915==" Return-path: List-Unsubscribe: , List-Post: List-Help: List-Subscribe: , Sender: xen-devel-bounces@lists.xensource.com Errors-To: xen-devel-bounces@lists.xensource.com To: =?utf-8?Q?konrad=2Ewilk?= Cc: =?utf-8?Q?xen-devel?= List-Id: xen-devel@lists.xenproject.org This is a multi-part message in MIME format. Your mail reader does not understand MIME message format. --===============5279143288043207915== Content-Type: multipart/alternative; boundary="=_YxzPBjBTzpUBlSYZQ4vSJPEqrKxiuQBmiORB-kDfPBPw5Qac" This is a multi-part message in MIME format. Your mail reader does not understand MIME message format. --=_YxzPBjBTzpUBlSYZQ4vSJPEqrKxiuQBmiORB-kDfPBPw5Qac Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: quoted-printable Hello again, I would like to come back to that thing...sorry that I did n= ot have the time up to now.=0D=0A=0D=0A=C2=A0=0D=0AWe (now) speak about=0D= =0A=0D=0A=C2=A0=0D=0A*=09Xen 4.1.2=0D=0A*=09Dom0 is Jeremy's 2.6.32.46 64= bit=0D=0A*=09DomU in question is now 3.1.2 64 bit=0D=0A*=09Same thing if= DomU is also 2.6.32.46=0D=0A*=09DomU owns two PCI cards (DVB-C) that o D= MA=0D=0A*=09Machine has 8GB, Dom0 pinned at 512MB=0D=0A=0D=0A=C2=A0=0D=0A= As compared to 2.6.34 Kernel with backported patches, the load on the Dom= U is at least twice as high. It=0D=0A=0D=0Awill be "close to normal" if I= reduce the memory used to 4GB.=0D=0A=0D=0A=C2=A0=0D=0AAs you can see fro= m the attachment, you once had an idea. So should we try to find somethin= g...=3F=0D=0A=0D=0A=C2=A0=0D=0ACarsten.=0D=0A=C2=A0=0D=0A-----Urspr=C3=BC= ngliche Nachricht-----=0D=0AAn:konrad.wilk ;=20=0D= =0ACC:linux ; xen-devel ;=20=0D=0AVon:Carsten Schiers =0D=0AGesendet:Mi 2= 9.06.2011 23:17=0D=0ABetreff:AW: Re: Re: Re: AW: Re: [Xen-devel] AW: Load= increase after memory upgrade=3F=0D=0A> Lets first do the c) experiment = as that will likely explain your load average increase.=0D=0A...=0D=0A> >= c). If you want to see if the fault here lies in the bounce buffer=20=0D=0A= > being used more=0D=0A> >often in the DomU b/c you have 8GB of memory no= w and you end up using=20=0D=0A> more pages=0D=0A> >past 4GB (in DomU), I= can cook up a patch to figure this out. But an=20=0D=0A> easier way is=0D= =0A> >to just do (on the Xen hypervisor line): mem=3D4G and that will mak= e=20=0D=0A> think you only have=0D=0A> >4GB of physical RAM. =C2=A0If the= load comes back to the normal "amount"=20=0D=0A> then the likely=0D=0A> = >culprit is that and we can think on how to fix this.=0D=0A=0D=0AYou are = on the right track. Load was going down to "normal" 10% when reducing=0D=0A= Xen to 4GB by the parameter. Load seems to be still a little, little bit = lower=0D=0Awith Xenified Kernel (8-9%), but this is drastically lower tha= n the 20% we had=0D=0Abefore.=0D=0A --=_YxzPBjBTzpUBlSYZQ4vSJPEqrKxiuQBmiORB-kDfPBPw5Qac Content-Type: text/html; charset=utf-8 Content-Transfer-Encoding: quoted-printable =0A=0A =0A =0A Load increase= after memory upgrade (part2)=0A =0A=0A=0A

Hello again, I = would like to come back to that thing...sorry that I did not have the tim= e up to now.

We (now) speak about

Xen 4.1.2
Dom0 is Jeremy's 2.6.32.46 64 bit
DomU = in question is now 3.1.2 64 bit
Same thing if DomU is also 2.6.32= =2E46
DomU owns two PCI cards (DVB-C) that o DMA
Machine = has 8GB, Dom0 pinned at 512MB

As compared to 2.6= =2E34 Kernel with backported patches, the load on the DomU is at least tw= ice as high. It

will be "close to normal" if I reduce the= memory used to 4GB.

As you can see from the attachmen= t, you once had an idea. So should we try to find something...=3F

&= nbsp;

Carsten.

-----Ursprünglic= he Nachricht-----
An:=09konrad.wilk <konrad.wilk= @oracle.com>;
CC:=09linux <linux@eikelenboom= =2Eit>; xen-devel <xen-devel@lists.xensource.com>;
Von:=09Carsten Schiers <carsten@schiers.de>
= Gesendet:=09Mi 29.06.2011 23:17
Betreff:=09= AW: Re: Re: Re: AW: Re: [Xen-devel] AW: Load increase after memory upgrad= e=3F
> Lets first do the c) experiment as that will likely explai= n your load average increase.
...
> >c). If you want to s= ee if the fault here lies in the bounce buffer
> being used more=
> >often in the DomU b/c you have 8GB of memory now and you e= nd up using
> more pages
> >past 4GB (in DomU), I can= cook up a patch to figure this out. But an
> easier way is
> >to just do (on the Xen hypervisor line): mem=3D4G and that will= make
> think you only have
> >4GB of physical RAM. &= nbsp;If the load comes back to the normal "amount"
> t= hen the likely
> >culprit is that and we can think on how to f= ix this.

You are on the right track. Load was going down to &q= uot;normal" 10% when reducing
Xen to 4GB by the parameter. Load= seems to be still a little, little bit lower
with Xenified Kernel (= 8-9%), but this is drastically lower than the 20% we had
before.

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