On Mon, Jul 25, 2011 at 12:24:55PM -0700, Radhya sahal wrote:
> --- On Mon, 7/25/11, Pasi Kärkkäinen <pasik@xxxxxx> wrote:
>
> T hank's Pasi ,
> I tried to run this command drop cache in VM and physical(dom0) before i
> put my question in the group !!!
> echo 3 >/proc/sys/vm/drop_caches
> dom0 actually empty cache but there is not any effect the files in VM
> still in the cache??
>
So then Xen dom0 is NOT caching anything.
Your problem is somewhere else!
Perhaps hardware RAID controller (with memory cache onboard) ?
-- Pasi
> 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"
> > on_poweroff = "destroy"
> > on_reboot = "restart"
> > on_crash = "restart"
> > 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 <[1]pasik@xxxxxx> wrote:
> >
> > From: Pasi Kärkkäinen <[2]pasik@xxxxxx>
> > Subject: Re: [Xen-users] how can empty xen disk cache??
> > To: "Radhya sahal" <[3]rad_cs_2006@xxxxxxxxx>
> > Cc: "xen list" <[4]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][5]pasik@xxxxxx>
> wrote:
> > >
> > > From: Pasi Kärkkäinen <[2][6]pasik@xxxxxx>
> > > Subject: Re: [Xen-users] how can empty xen disk cache??
> > > To: "Mark Pryor" <[3][7]tlviewer@xxxxxxxxx>
> > > Cc: "Radhya sahal" <[4][8]rad_cs_2006@xxxxxxxxx>,
> > > "[5][9]xen-users@xxxxxxxxxxxxxxxxxxx"
> > <[6][10]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][11]rad_cs_2006@xxxxxxxxx>
> > > > To: [8][12]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=[13]pasik@xxxxxx
> > 2. file:///mc/compose?to=[14]pasik@xxxxxx
> > 3. file:///mc/compose?to=[15]tlviewer@xxxxxxxxx
> > 4. file:///mc/compose?to=[16]rad_cs_2006@xxxxxxxxx
> > 5. file:///mc/compose?to=[17]xen-users@xxxxxxxxxxxxxxxxxxx
> > 6. file:///mc/compose?to=[18]xen-users@xxxxxxxxxxxxxxxxxxx
> > 7. file:///mc/compose?to=[19]rad_cs_2006@xxxxxxxxx
> > 8. file:///mc/compose?to=[20]xen-users@xxxxxxxxxxxxxxxxxxx
>
> References
>
> Visible links
> 1. file:///mc/compose?to=pasik@xxxxxx
> 2. file:///mc/compose?to=pasik@xxxxxx
> 3. file:///mc/compose?to=rad_cs_2006@xxxxxxxxx
> 4. file:///mc/compose?to=xen-users@xxxxxxxxxxxxxxxxxxx
> 5. file:///mc/compose?to=pasik@xxxxxx
> 6. file:///mc/compose?to=pasik@xxxxxx
> 7. file:///mc/compose?to=tlviewer@xxxxxxxxx
> 8. file:///mc/compose?to=rad_cs_2006@xxxxxxxxx
> 9. file:///mc/compose?to=xen-users@xxxxxxxxxxxxxxxxxxx
> 10. file:///mc/compose?to=xen-users@xxxxxxxxxxxxxxxxxxx
> 11. file:///mc/compose?to=rad_cs_2006@xxxxxxxxx
> 12. file:///mc/compose?to=xen-users@xxxxxxxxxxxxxxxxxxx
> 13. file:///mc/compose?to=pasik@xxxxxx
> 14. file:///mc/compose?to=pasik@xxxxxx
> 15. file:///mc/compose?to=tlviewer@xxxxxxxxx
> 16. file:///mc/compose?to=rad_cs_2006@xxxxxxxxx
> 17. file:///mc/compose?to=xen-users@xxxxxxxxxxxxxxxxxxx
> 18. file:///mc/compose?to=xen-users@xxxxxxxxxxxxxxxxxxx
> 19. file:///mc/compose?to=rad_cs_2006@xxxxxxxxx
> 20. file:///mc/compose?to=xen-users@xxxxxxxxxxxxxxxxxxx
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