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Re: [Xen-users] dynamic memory extension not working on Debian Squeeze


  • To: xen-users@xxxxxxxxxxxxx
  • From: Alexandre Kouznetsov <alk@xxxxxxxxxx>
  • Date: Thu, 15 Nov 2012 13:18:12 -0600
  • Delivery-date: Thu, 15 Nov 2012 19:19:46 +0000
  • List-id: Xen user discussion <xen-users.lists.xen.org>

El 15/11/12 03:20, Ian Campbell escribió:
When I asked for "xenstore-ls -fp | grep target" I meant the literal
string "target" not the name of the target VM, sorry if this wasn't
clear!
lol.

To avoid confusion, I'll post the complete reference once again.

# At the beginning, the DomU is not running.
root@on05:~# uname -a
Linux on05 2.6.32-5-xen-amd64 #1 SMP Sun Sep 23 13:49:30 UTC 2012 x86_64 GNU/Linux
root@on05:~# dpkg -la|grep xen|awk '{print $1"\t "$2"\t"$3}'
ii     libxenstore3.0    4.0.1-5.4
ii     linux-image-2.6.32-5-xen-amd64    2.6.32-46
ii     xen-hypervisor-4.0-amd64    4.0.1-5.4
ii     xen-linux-system-2.6.32-5-xen-amd64    2.6.32-46
ii     xen-qemu-dm-4.0    4.0.1-2+squeeze2
ii     xen-tools    4.2-1
ii     xen-utils-4.0    4.0.1-5.4
ii     xen-utils-common    4.0.0-1
ii     xenstore-utils    4.0.1-5.4
ii     xenwatch    0.5.4-2
root@on05:~# xenstore-ls -fp | grep target
/local/domain/0/memory/target = "759040"   (n0)
/local/domain/1/memory/target = "2097152"   (n1)
/local/domain/2/memory/target = "3145728"   (n2)
/local/domain/3/memory/target = "2097152"   (n3)
/local/domain/4/memory/target = "8388608"   (n4)
/local/domain/5/memory/target = "3145728"   (n5)
/local/domain/6/memory/target = "2097152"   (n6)
/local/domain/7/memory/target = "3145728"   (n7)
/local/domain/8/memory/target = "2097152"   (n8)
/local/domain/13/memory/target = "262144"   (n13)
root@on05:~# cat /etc/xen/scoutapi-dev.cfg
#
# Configuration file for the Xen instance scoutapi-dev, created
# by xen-tools 4.2 on Tue Nov 13 19:09:45 2012.
name        = 'scoutapi-dev'
memory      = '256'
maxmem      = '8192'
vcpus       = '1'
kernel      = '/boot/vmlinuz-2.6.32-5-xen-amd64'
ramdisk     = '/boot/initrd.img-2.6.32-5-xen-amd64'
root        = '/dev/xvda2 ro'
disk        = [
                  'phy:/dev/r5VG/scoutapi-dev-srv,xvda3,w',
                  'phy:/dev/r5VG/scoutapi-dev-root,xvda2,w',
                  'phy:/dev/r5VG/scoutapi-dev-swap,xvda1,w',
              ]
vif         = [
                'ip=11.22.33.44,mac=00:16:3E:DB:81:C3,bridge=xenbr18',
              ]
on_poweroff = 'destroy'
on_reboot   = 'restart'
on_crash    = 'restart'
root@on05:~# xm dmesg
[ ... output attached as Xen_xm_dmesg.txt ... ]
root@on05:~# xm create /etc/xen/scoutapi-dev.cfg
Using config file "/etc/xen/scoutapi-dev.cfg".
Started domain scoutapi-dev (id=14)


# This outputs only things that appear in dmesg
# specifically after "xm create"
root@on05:~# dmesg | grep -A 200 "3157705.503671"
[3157705.503671] device vif14.0 entered promiscuous mode
[3157705.506756] xenbr18: port 9(vif14.0) entering learning state
[3157705.530745] physdev match: using --physdev-out in the OUTPUT, FORWARD and POSTROUTING chains for non-bridged traffic is not supported anymore.
[ ... cut 87 more lines like the previous one, another issue ... ]
[3157708.410438] blkback: ring-ref 8, event-channel 8, protocol 1 (x86_64-abi) [3157708.437015] blkback: ring-ref 9, event-channel 9, protocol 1 (x86_64-abi) [3157708.458983] blkback: ring-ref 10, event-channel 10, protocol 1 (x86_64-abi)
[3157715.680703] vif14.0: no IPv6 routers present
[3157720.504649] xenbr18: port 9(vif14.0) entering forwarding state
root@on05:~# sleep 20
root@on05:~# xm list | grep scoutapi-dev
scoutapi-dev                    14   256     1     -b----      2.5
root@on05:~# xenstore-ls -fp | grep target
/local/domain/0/memory/target = "759040"   (n0)
/local/domain/1/memory/target = "2097152"   (n1)
/local/domain/2/memory/target = "3145728"   (n2)
/local/domain/3/memory/target = "2097152"   (n3)
/local/domain/4/memory/target = "8388608"   (n4)
/local/domain/5/memory/target = "3145728"   (n5)
/local/domain/6/memory/target = "2097152"   (n6)
/local/domain/7/memory/target = "3145728"   (n7)
/local/domain/8/memory/target = "2097152"   (n8)
/local/domain/13/memory/target = "262144"   (n13)
/local/domain/14/memory/target = "262144"   (n14)

# I guess the "(n14)" is the interesting line from now on

# Now, this is a just-booted DomU.
# It uses Dom0's initrd, so dmesg might show strange stuff.
# Although, there is no software RAID in this Dom0, now or ever.
root@scoutapi-dev:~# dmesg
[ ... output attached as DomU_dmesg.txt ... ]
root@scoutapi-dev:~# cat /proc/meminfo |grep MemTotal
MemTotal:         258908 kB
root@scoutapi-dev:~# cat /sys/devices/system/xen_memory/xen_memory0/target_kb
262144

# Grow DomU's memory from Dom0
root@on05:~# xm mem-set scoutapi-dev 512
root@on05:~# xm list|grep scoutapi-dev
scoutapi-dev                    14   512     1     -b----      2.9
root@on05:~# xenstore-ls -fp | grep target | grep "(n14)"
/local/domain/14/memory/target = "524288"   (n14)
root@on05:~# xm dmesg
[ ... no change, it ends at "Freed 176kB init memory" ... ]
root@on05:~# dmesg | grep -A 200 "3157705.503671"
[ ... no change, it ends at 3157720.504649 ... ]

# Let's see DomU
# I've reviewed my previous e-mail, I probably mistyped something there.
# "target_kb" showed here is the correct one, double checked.
root@scoutapi-dev:~# dmesg
[ ... no change, it ends at 14.636018 ... ]
root@scoutapi-dev:~# cat /proc/meminfo |grep MemTotal
MemTotal:         258908 kB
root@scoutapi-dev:~# cat /sys/devices/system/xen_memory/xen_memory0/target_kb
524288
root@scoutapi-dev:~# dpkg -la|grep udev|awk '{print $1"\t "$2"\t"$3}'
ii       libudev0       164-3
ii       udev   164-3
# Do not know if udev is relevant.
# Also, the mem-set event has not been reflected anywhere
# under DomU's /var/log


# Now shrink DomU's memory
root@on05:~# xm mem-set scoutapi-dev 128
root@on05:~# xm list|grep scoutapi-dev
scoutapi-dev                    14   128     1     -b----      3.2
root@on05:~# xenstore-ls -fp | grep target | grep "(n14)"
/local/domain/14/memory/target = "131072"   (n14)
root@on05:~# xm dmesg
[ ... no change, it ends at "Freed 176kB init memory" ... ]
root@on05:~# dmesg | grep -A 200 "3157705.503671"
[ ... no change, it ends at 3157720.504649 ... ]

# Let's see DomU, it's shrinked correctly
root@scoutapi-dev:~# dmesg
[ ... no change, it ends at 14.636018 ... ]
root@scoutapi-dev:~# cat /proc/meminfo |grep MemTotal
MemTotal:         131676 kB
root@scoutapi-dev:~# cat /sys/devices/system/xen_memory/xen_memory0/target_kb
131072

# Return to original DomU's memory
root@on05:~# xm mem-set scoutapi-dev 256
root@on05:~# xm list|grep scoutapi-dev
scoutapi-dev                    14   256     1     -b----      3.3
root@on05:~# xenstore-ls -fp | grep target | grep "(n14)"
/local/domain/14/memory/target = "262144"   (n14)

# DomU has recovered correctly
root@scoutapi-dev:~# dmesg
[ ... no change, it ends at 14.636018 ... ]
root@scoutapi-dev:~# cat /proc/meminfo |grep MemTotal
MemTotal:         258908 kB
root@scoutapi-dev:~# cat /sys/devices/system/xen_memory/xen_memory0/target_kb
262144


root@on05:~# xentop
xentop - 13:15:07   Xen 4.0.1
11 domains: 3 running, 8 blocked, 0 paused, 0 crashed, 0 dying, 0 shutdown
Mem: 33541220k total, 27887596k used, 5653624k free    CPUs: 24 @ 2400MHz
[ ... cut beyond header ... ]
root@on05:~# cat /var/log/xen/xend.log | grep -A 200 "Domain scoutapi-dev (14) unpaused." [2012-11-15 12:17:00 3286] INFO (XendDomain:1206) Domain scoutapi-dev (14) unpaused. [2012-11-15 12:39:58 3286] DEBUG (XendDomainInfo:1477) Setting memory target of domain scoutapi-dev (14) to 512 MiB. [2012-11-15 12:52:30 3286] DEBUG (XendDomainInfo:1477) Setting memory target of domain scoutapi-dev (14) to 128 MiB. [2012-11-15 12:55:08 3286] DEBUG (XendDomainInfo:1477) Setting memory target of domain scoutapi-dev (14) to 256 MiB.

Nothing new in Dom0's xen-hotplug.log or xend-debug.log.

Well, it's clear that the memory change, when It's increased beyond the original size, is _detectable_ under DomU, but it's kernel does not takes it into account. Any changes under the original size are seem to be processed normally. That is so far as I went in debugging.

What else could be relevant?


--
Alexandre Kouznetsov

Attachment: Xen_xm_dmesg.txt
Description: Text document

Attachment: DomU_dmesg.txt
Description: Text document

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