Op 3-4-2012 10:28, Andrey Korolyov schreef:
But I am able to set static limits in the config for rbd :) All I want
is a change on-the-fly.
It is NOT cgroups mechanism, but completely qemu-driven.
Are you sure about that?
http://libvirt.org/formatdomain.html#elementsBlockTuning
Browsing through the source code I found that this is indeed related to
libvirt.
In the Qemu driver:
if (disk->type != VIR_DOMAIN_DISK_TYPE_BLOCK &&
disk->type != VIR_DOMAIN_DISK_TYPE_FILE)
goto cleanup;
...
...
cleanup:
if (!ret) {
qemuReportError(VIR_ERR_INVALID_ARG,
"%s", _("No device found for specified path"));
}
RBD devices are however of the type: VIR_DOMAIN_DISK_TYPE_NETWORK
That's why you get this error, it's assuming the device you want to set
the limits on is a block device or a regular file.
Wido
On Tue, Apr 3, 2012 at 12:21 PM, Wido den Hollander<wido@xxxxxxxxx> wrote:
Hi,
Op 3-4-2012 10:02, Andrey Korolyov schreef:
Hi,
# virsh blkdeviotune Test vdb --write_iops_sec 50 //file block device
# virsh blkdeviotune Test vda --write_iops_sec 50 //rbd block device
error: Unable to change block I/O throttle
error: invalid argument: No device found for specified path
That is correct. As far as I know iotune uses the underlying cgroups from
the OS.
RBD devices (when using Qemu) are not block devices which can be managed by
cgroups. That's why it's not working and you get the error that the device
can't be found.
There is however somebody working on DiskIoThrottling inside Qemu:
http://wiki.qemu.org/Features/DiskIOLimits
That would work with RBD (he even names Ceph :) )
Wido
2012-04-03 07:38:49.170+0000: 30171: debug :
virDomainSetBlockIoTune:18317 : dom=0x1114590, (VM: name=Test,
uuid=8c27bf32-82dc-315a-d0ba-4653b1b3d595), disk=vda,
params=0x1114600, nparams=1, flags=0
2012-04-03 07:38:49.170+0000: 30169: debug :
virEventPollMakePollFDs:383 : Prepare n=8 w=11, f=16 e=1 d=0
2012-04-03 07:38:49.170+0000: 30169: debug :
virEventPollCalculateTimeout:325 : Calculate expiry of 4 timers
2012-04-03 07:38:49.170+0000: 30169: debug :
virEventPollCalculateTimeout:331 : Got a timeout scheduled for
1333438734170
2012-04-03 07:38:49.170+0000: 30171: error : qemuDiskPathToAlias:11338
: invalid argument: No device found for specified path
2012-04-03 07:38:49.170+0000: 30171: debug : virDomainFree:2313 :
dom=0x1114590, (VM: name=Test,
uuid=8c27bf32-82dc-315a-d0ba-4653b1b3d595)
2012-04-03 07:38:49.170+0000: 30171: debug : virUnrefDomain:276 :
unref domain 0x1114590 Test 1
2012-04-03 07:38:49.170+0000: 30171: debug : virReleaseDomain:238 :
release domain 0x1114590 Test 8c27bf32-82dc-315a-d0ba-4653b1b3d595
2012-04-03 07:38:49.170+0000: 30169: debug :
virEventPollCalculateTimeout:351 : Timeout at 1333438734170 due in
5000 ms
2012-04-03 07:38:49.170+0000: 30169: debug : virEventPollRunOnce:619 :
EVENT_POLL_RUN: nhandles=9 imeout=5000
2012-04-03 07:38:49.170+0000: 30171: debug : virReleaseDomain:246 :
unref connection 0x1177b10 2
libvir 0.9.10, json-escape patch applied, but seems that this problem
related to another incorrect path handle.
I`m in doubt if it belongs to libvirt ml or here.
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