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Re: [Qemu-devel] [PATCH V9 06/12] NUMA: Add Linux libnuma detection
From: |
Wanlong Gao |
Subject: |
Re: [Qemu-devel] [PATCH V9 06/12] NUMA: Add Linux libnuma detection |
Date: |
Thu, 29 Aug 2013 10:22:46 +0800 |
User-agent: |
Mozilla/5.0 (X11; Linux x86_64; rv:17.0) Gecko/20130805 Thunderbird/17.0.8 |
On 08/28/2013 09:44 PM, Paolo Bonzini wrote:
> Il 26/08/2013 10:43, Andrew Jones ha scritto:
>>
>> ----- Original Message -----
>>>> On 08/26/2013 03:46 PM, Andrew Jones wrote:
>>>>>>>>>> Is this patch still necessary? I thought that dropping the
>>>>>>>>>>>>>> numa_num_configured_nodes() calls from patch 8/12 got rid
>>>>>>>>>>>>>> of the need for this library. Maybe I missed other uses?
>>>>>>>>>>
>>>>>>>>>> Yes, in 08/12 we also use mbind(),
>>>>>> You don't need a whole library for mbind(), it's a syscall. See
>>>>>> syscall(2).
>>>>>>
>>>>>>>>>> and in 09/12 we use max_numa_node().
>>>>>> Really? I didn't see it there. And anyway, that goes back to our
>>>>>> discussion
>>>>>> about setting qemu's MAX_NODES to whatever we think qemu should support,
>>>>>> and then just checking that we don't blow that limit whenever reading
>>>>>> host node info, i.e.
>>>>>>
>>>>>> maxnode = 0;
>>>>>> while (host_nodes[maxnode] && maxnode < MAX_NODES)
>>>>>> node_read(&info[maxnode++]);
>>>>>>
>>>>>> type of a thing.
>>>>>>
>>>>>> And, if there's a place you really need to know the current online number
>>>>>> of host nodes, then, like I said earlier, you should just go to sysfs
>>>>>> yourself. libnuma:numa_max_node() returns an int that it only initializes
>>>>>> at library load time, so it's not going to adapt to onlining/offlining.
>>>>
>>>> OK, thank you.
>>>> Then I should define MPOL_* macros in QEMU and use mbind(2) syscall
>>>> directly,
>>>> right?
>> Hmm, yeah, that's too bad that numaif.h is part of libnuma, and not a more
>> general lib. Whether or not we want to redefine those symbols within
>> qemu, in order to avoid the dependency on installing numactl-devel, isn't
>> something I can answer. That's a better question for Anthony. Anthony? Paolo,
>> any opinions? Maybe we should pick up uapi/linux/mempolicy.h with the
>> linux-header synch script?
>>
>
> I think using libnuma is fine. In principle this could be used on other
> OSes than Linux, I think?
But seems that mbind(2) is Linux-specific syscall, right?
Thanks,
Wanlong Gao
>
> Paolo
>
- [Qemu-devel] [PATCH V9 01/12] NUMA: add NumaOptions, NumaNodeOptions and NumaMemOptions, (continued)
- [Qemu-devel] [PATCH V9 01/12] NUMA: add NumaOptions, NumaNodeOptions and NumaMemOptions, Wanlong Gao, 2013/08/23
- [Qemu-devel] [PATCH V9 04/12] NUMA: move numa related code to numa.c, Wanlong Gao, 2013/08/23
- [Qemu-devel] [PATCH V9 05/12] NUMA: Add numa_info structure to contain numa nodes info, Wanlong Gao, 2013/08/23
- [Qemu-devel] [PATCH V9 06/12] NUMA: Add Linux libnuma detection, Wanlong Gao, 2013/08/23
- Re: [Qemu-devel] [PATCH V9 06/12] NUMA: Add Linux libnuma detection, Andrew Jones, 2013/08/23
- Re: [Qemu-devel] [PATCH V9 06/12] NUMA: Add Linux libnuma detection, Wanlong Gao, 2013/08/25
- Re: [Qemu-devel] [PATCH V9 06/12] NUMA: Add Linux libnuma detection, Andrew Jones, 2013/08/26
- Re: [Qemu-devel] [PATCH V9 06/12] NUMA: Add Linux libnuma detection, Wanlong Gao, 2013/08/26
- Re: [Qemu-devel] [PATCH V9 06/12] NUMA: Add Linux libnuma detection, Andrew Jones, 2013/08/26
- Re: [Qemu-devel] [PATCH V9 06/12] NUMA: Add Linux libnuma detection, Paolo Bonzini, 2013/08/28
- Re: [Qemu-devel] [PATCH V9 06/12] NUMA: Add Linux libnuma detection,
Wanlong Gao <=
- Re: [Qemu-devel] [PATCH V9 06/12] NUMA: Add Linux libnuma detection, Andrew Jones, 2013/08/29
- Re: [Qemu-devel] [PATCH V9 06/12] NUMA: Add Linux libnuma detection, Andrew Jones, 2013/08/29
[Qemu-devel] [PATCH V9 08/12] NUMA: set guest numa nodes memory policy, Wanlong Gao, 2013/08/23
[Qemu-devel] [PATCH V9 07/12] NUMA: parse guest numa nodes memory policy, Wanlong Gao, 2013/08/23
[Qemu-devel] [PATCH V9 10/12] NUMA: add hmp command set-mem-policy, Wanlong Gao, 2013/08/23
[Qemu-devel] [PATCH V9 03/12] NUMA: check if the total numa memory size is equal to ram_size, Wanlong Gao, 2013/08/23