Re: [Qemu-devel] [PATCH] numa, spapr: align default numa node memory size to 256MB

[Laurent Vivier]

On 20/03/2017 12:31, Thomas Huth wrote:
> On 20.03.2017 12:24, Laurent Vivier wrote:
>> Since commit 224245b ("spapr: Add LMB DR connectors"), NUMA node
>> memory size must be aligned to 256MB (SPAPR_MEMORY_BLOCK_SIZE).
>>
>> But when "-numa" option is provided without "mem" parameter,
>> the memory is equally divided between nodes, but 8MB aligned.
>> This can be not valid for pseries.
>>
>> In that case we can have:
>> $ ./ppc64-softmmu/qemu-system-ppc64 -m 4G -numa node -numa node -numa node
>> qemu-system-ppc64: Node 0 memory size 0x55000000 is not aligned to 256 MiB
>>
>> With this patch, we have:
>> (qemu) info numa
>> 3 nodes
>> node 0 cpus: 0
>> node 0 size: 1280 MB
>> node 1 cpus:
>> node 1 size: 1280 MB
>> node 2 cpus:
>> node 2 size: 1536 MB
>>
>> Signed-off-by: Laurent Vivier <address@hidden>
>> ---
>>  dtc    |  2 +-
>>  numa.c | 14 +++++++++-----
>>  2 files changed, 10 insertions(+), 6 deletions(-)
>>
>> diff --git a/dtc b/dtc
>> index 558cd81..fa8bc7f 160000
>> --- a/dtc
>> +++ b/dtc
>> @@ -1 +1 @@
>> -Subproject commit 558cd81bdd432769b59bff01240c44f82cfb1a9d
>> +Subproject commit fa8bc7f928ac25f23532afc8beb2073efc8fb063
> 
> Accidential change?
> 
>> diff --git a/numa.c b/numa.c
>> index e01cb54..a911284 100644
>> --- a/numa.c
>> +++ b/numa.c
>> @@ -337,15 +337,19 @@ void parse_numa_opts(MachineClass *mc)
>>          }
>>          if (i == nb_numa_nodes) {
>>              uint64_t usedmem = 0;
>> -
>> -            /* On Linux, each node's border has to be 8MB aligned,
>> -             * the final node gets the rest.
>> -             */
>> +#if defined(TARGET_PPC64)
>> +            /* pseries requests each node's border has to be 256 MB aligned 
>> */
>> +            const uint64_t numa_mem_align_mask = ~((1 << 28UL) - 1);
>> +#else
>> +            /* On Linux, each node's border has to be 8MB aligned */
>> +            const uint64_t numa_mem_align_mask = ~((1 << 23UL)  - 1);
>> +#endif
> 
> With that #if, you enable this for all ppc machines, not just for the
> pseries machine. So it might be cleaner to add a setting to the
> MachineClass instead...?
> 

I will rework that. But I thought the only PPC64 machine able to boot
with "-numa"  is pseries.

Thanks,
Laurent