On Sun, Jul 24, 2011 at 08:45:49AM -0700, Radhya sahal wrote:
> HI Pasi,
> thanks for your cooperation,this the XML configuration VM file
> name = "vm2"
> uuid = "70bf5c52-91ed-fbd5-4eb7-f6acc52c3168"
> maxmem = 2277
> memory = 1024
> vcpus =
1
> bootloader = "/usr/bin/pygrub"
> kernel = "/var/lib/xen/boot_kernel.313tN4"
> ramdisk = "/var/lib/xen/boot_ramdisk.vV9Kd9"
> extra = "ro root=/dev/VolGroup00/LogVol00 rhgb quiet"
>
>
>
> vfb = [ "type=vnc,vncunused=1,keymap=en-us" ]
> disk = [ "tap:aio:/var/lib/xen/images/vm2.img,xvda,w" ]
> vif = [
> "mac=00:16:36:1e:3a:dc,bridge=virbr0,script=vif-bridge,vifname=vif2.0" ]
> i am new user for xen so i think maybe you the backend in xen tap:aio ??
> how can be sure the VM cache is empty with out restart VM??
>
So yeah, you're using tap:aio: backend.
You shouldn't have any dom0 caching then.
Do you
perhaps have a RAID controller with memory cache module?
You could try running the "drop caches" in dom0, and see if that changes anything..
-- Pasi
>
> --- On Sun, 7/24/11, Pasi Kärkkäinen <
pasik@xxxxxx> wrote:
>
> From: Pasi Kärkkäinen <
pasik@xxxxxx>
> Subject: Re: [Xen-users] how can empty xen disk cache??
> To: "Radhya sahal" <
rad_cs_2006@xxxxxxxxx>
> Cc: "xen list" <
xen-users@xxxxxxxxxxxxxxxxxxx>
> Date:
Sunday, July 24, 2011, 3:21 AM
>
> On Sat, Jul 23, 2011 at 06:46:58PM -0700, Radhya sahal wrote:
> > thank's Mark and Pasi,
> > i use centos and xen ,either dom0 and vm run centos 5.5.
> > in the vm i run java application which it reads e.g( text file ,table
> in
> > database,....).
> > in the first read get actual total run-time but if i try to read more
> than
> > one . the file be in cache and get a very very short time ..!!!
> > although i try to empty the vm cache and physical(dom0) cache!!!
> > echo 3
>/proc/sys/vm/drop_caches
> > i want to read more than one to calculate the the right average
> run-time for
> > the vm resource allocation and compare this averages with other vm
> resource
> > allocations ???
> >
>
> I repeat the question: Which disk backend are you using in dom0 for the VM
> ?
>
> -- Pasi
>
> > --- On Sat, 7/23/11, Pasi Kärkkäinen <[1]
pasik@xxxxxx> wrote:
> >
> > From: Pasi Kärkkäinen <[2]
pasik@xxxxxx>
> > Subject: Re: [Xen-users] how can empty xen disk cache??
> > To: "Mark Pryor" <[3]
tlviewer@xxxxxxxxx>
> > Cc: "Radhya sahal" <[4]
rad_cs_2006@xxxxxxxxx>,
> > "[5]
xen-users@xxxxxxxxxxxxxxxxxxx"
> <[6]
xen-users@xxxxxxxxxxxxxxxxxxx>
> >
Date: Saturday, July 23, 2011, 6:44 AM
> >
> > On Fri, Jul 22, 2011 at 07:11:57PM -0700, Mark Pryor wrote:
> > >
> >
> --------------------------------------------------------------------------
> > >
> > > From: Radhya sahal <[7]
rad_cs_2006@xxxxxxxxx>
> > > To: [8]
xen-users@xxxxxxxxxxxxxxxxxxx> > > Sent: Friday, July 22, 2011 5:36
PM
> > > Subject: [Xen-users] how can empty xen disk cache??
> > >
> > > hi
> > > I am new user for xen
> > > i have VM and i run java application on it ..
> > > i want to empty cache for vm
> > > i do that with
> > > echo 3 >/proc/sys/vm/drop_caches
> > > and the same command in physical machine
> > > but there is not any
effect
> > > i think the vm have own cache in xen
> > > how can empty xen disk cache??
> > > thanks
> > >
> > > check options in /etc/sysconfig/xendomains or (etc/default --
> in
> > debian)
> > > and turn off save/restore.
> > >
> >
> > I don't think the question has nothing to do with save/restore.
> >
> >
Dom0 does not usually cache domU disk IO, unless you're using file:
> > backend.
> > Which disk backends are you using?
> >
> > tap:aio and phy: backends bypass the dom0 page cache,
> > and thus those backends don't have any caching in xen dom0.
> >
> > Xen hypervisor itself does not have cache of any kind.
> >
> > -- Pasi
>
> References
>
> Visible links
> 1. file:///mc/compose?to=
pasik@xxxxxx> 2. file:///mc/compose?to=
pasik@xxxxxx> 3. file:///mc/compose?to=
tlviewer@xxxxxxxxx> 4. file:///mc/compose?to=
rad_cs_2006@xxxxxxxxx> 5. file:///mc/compose?to=
xen-users@xxxxxxxxxxxxxxxxxxx> 6. file:///mc/compose?to=
xen-users@xxxxxxxxxxxxxxxxxxx> 7. file:///mc/compose?to=
rad_cs_2006@xxxxxxxxx> 8. file:///mc/compose?to=
xen-users@xxxxxxxxxxxxxxxxxxx
