Re: [libvirt] [PATCH] qemu: don't setup cpuset.mems if memory mode in numatune is 'preferred'

On 2014/11/4 22:04, Martin Kletzander wrote: > On Tue, Nov 04, 2014 at 09:22:22PM +0800, Wang Rui wrote: >> If the memory mode is specified as preferred, we get the following error when >> starting domain. >> >> error: Unable to write to '$my_cgroup_path/cpuset.mems': Device or resource busy >> >> XML is configured with numatune as follows: >> <numatune> >> <memory mode='preferred' nodeset='0'/> >> </numatune> >> >> If memory mode is 'preferred', cpuset.mems in cgroup shouldn't be set to >> 'nodeset'. I find that maybe commit 1a7be8c600905aa07ac2d78293336ba8523ad48e >> changes the former logic of checking mode in virDomainNumatuneGetNodeset. >> >> Signed-off-by: Wang Rui <moon.wangrui(a)huawei.com&gt; >> --- >> src/qemu/qemu_cgroup.c | 5 +++++ >> 1 file changed, 5 insertions(+) >> > > Thanks for catching that, it definitely is a problem, but I think it > is cause by commit 93e82727ec11d471d2ef3a18835e1fdfe062cef1. > > It should be also fixed in virLXCCgroupSetupCpusetTune() for LXC. > OK. I'll try to fix it for LXC in another patch.

>> diff --git a/src/qemu/qemu_cgroup.c b/src/qemu/qemu_cgroup.c >> index b5bdb36..8685d6f 100644 >> --- a/src/qemu/qemu_cgroup.c >> +++ b/src/qemu/qemu_cgroup.c >> @@ -618,6 +618,11 @@ qemuSetupCpusetMems(virDomainObjPtr vm, >> if (!virCgroupHasController(priv->cgroup, VIR_CGROUP_CONTROLLER_CPUSET)) >> return 0; >> >> + if (virDomainNumatuneGetMode(vm->def->numatune, -1) != >> + VIR_DOMAIN_NUMATUNE_MEM_STRICT) { >> + return 0; >> + } >> + > > One question, is it problem only for 'preferred' or 'interleaved' as > well? Because if it's only problem for 'preferred', then the check is > wrong. If it's problem for 'interleaved' as well, then the commit > message is wrong. > 'interleave' with a single node(such as nodeset='0') will cause the same error. But 'interleave' mode should not live with a single node. So maybe there's another bugfix to check 'interleave' with single node.

If configured with 'interleave' and multiple nodes(such as nodeset='0-1'), VM can be started successfully. And cpuset.mems is set to the same nodeset. So I'll revise my patch. I'll send patches V2. Conclusion: 1/3 : add check for 'interleave' mode with single numa node 2/3 : fix this problem in qemu 3/3 : fix this problem in lxc Is it OK? > Anyway, after either one is fixed, I can push this. > > Thank you, > Martin