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Re: [libvirt-users] How to lookup the driver instance through virConnectPtr pointer



On 11/21/2012 05:34 PM, Daniel P. Berrange wrote:
On Wed, Nov 21, 2012 at 05:24:18PM +0800, Dennis Chen wrote:
Hi,

I plan to use virCgroupSetCpuCfsPeriod() and
virCgroupSetCpuCfsQuota() to control cpu bandwidth with help of
cgroup,
so I need to instantiate the cgroup parameter first for the calling
of virCgroupSetCpuCfsPeriod, below is my code piece:

1        virConnectPtr conn;
2        struct qemud_driver *driver;

3        conn = virConnectOpen("qemu:///system");
4        driver = conn->privateData;
5        virCgroupSetCpuCfsPeriod(driver->cgroup, cfs_period);

then I get an compiling error in line 4:
error: dereferencing pointer to incomplete type

I know the reason is the actual definition of virConnectPtr is in
datatyps.h, but it's not reasonable or ugly to include this file in
my project.
datatypes.h is an internal *private* header file which applications
cannot use.

So my question is, is there any API that I can get the driver
instance from virConnectPtr conn in the libvirt?
No, this is internal code. Your connection to libvirtd goes over an
RPC protocol, so there is no way for you to directly access this.
You must only use the public APis in libvirt.h or virterror.h

Daniel

Yeah, I know. So the email is try to get to know how to use cgroup to configure the cpu bandwidth of a specific VM, I am writing a separate project to control the cfs bandwidth of a VM specified, not taking use of the virsh shell.

Any tips?

Thanks,
Dennis


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