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Re: [Qemu-devel] [PATCH qemu] sysemu: support up to 1024 vCPUs
From: |
Alexey Kardashevskiy |
Subject: |
Re: [Qemu-devel] [PATCH qemu] sysemu: support up to 1024 vCPUs |
Date: |
Mon, 24 Oct 2016 12:53:10 +1100 |
User-agent: |
Mozilla/5.0 (X11; Linux x86_64; rv:45.0) Gecko/20100101 Thunderbird/45.2.0 |
On 19/10/16 23:23, Igor Mammedov wrote:
> On Wed, 19 Oct 2016 10:39:12 +1100
> Alexey Kardashevskiy <address@hidden> wrote:
>
>> On 18/10/16 22:00, Igor Mammedov wrote:
>>> On Tue, 11 Oct 2016 09:19:10 +1100
>>> Alexey Kardashevskiy <address@hidden> wrote:
>>>
>>>> Ping, anyone?
>>> I have a similar patch
>>> http://patchwork.ozlabs.org/patch/681709/
>>> which bumps limit to 288 and does a little bit more
>>> so it wouldn't affect current users.
>>
>> Why 288 (not oldlimit<<n)? :)
> That's how many vCPU we plan to support for target-i386.
So that patch from patchworks should actually be 3 patches -
- untie MAX_CPUMASK_BITS from maxcpus;
- increase MAX_CPUMASK_BITS to 1024 (till we get this thing totally dynamic);
- increase maxcpus for x86 to 288.
and on top of this I (or Greg) would repost pseries change to maxcpus=1024
Correct? Has your patch gone anywhere yet?
>
>
>> What does happen to the Greg's patch now?
> it could be amended to apply top of above patch,
>
> where it would change not only MAX_CPUMASK_BITS but also
> maxcpus in ppc target since above patch unties maxcpus
> from MAX_CPUMASK_BITS for all targets.
>
> So followup increases of MAX_CPUMASK_BITS won't affect
> other targets.
>
>>
>>
>>>
>>> After that's merged, I plan to get rid of this limit and
>>> make that part of numa parsing code dynamic so that it
>>> wouldn't impose such limit/any limits on target code.
>>>
>>>>
>>>>
>>>> On 04/10/16 11:33, Alexey Kardashevskiy wrote:
>>>>> From: Greg Kurz <address@hidden>
>>>>>
>>>>> Some systems can already provide more than 255 hardware threads.
>>>>>
>>>>> Bumping the QEMU limit to 1024 seems reasonable:
>>>>> - it has no visible overhead in top;
>>>>> - the limit itself has no effect on hot paths.
>>>>>
>>>>> Signed-off-by: Greg Kurz <address@hidden>
>>>>> Signed-off-by: Alexey Kardashevskiy <address@hidden>
>>>>> ---
>>>>> include/sysemu/sysemu.h | 2 +-
>>>>> 1 file changed, 1 insertion(+), 1 deletion(-)
>>>>>
>>>>> diff --git a/include/sysemu/sysemu.h b/include/sysemu/sysemu.h
>>>>> index ef2c50b..2ec0bd8 100644
>>>>> --- a/include/sysemu/sysemu.h
>>>>> +++ b/include/sysemu/sysemu.h
>>>>> @@ -173,7 +173,7 @@ extern int mem_prealloc;
>>>>> *
>>>>> * Note that cpu->get_arch_id() may be larger than MAX_CPUMASK_BITS.
>>>>> */
>>>>> -#define MAX_CPUMASK_BITS 255
>>>>> +#define MAX_CPUMASK_BITS 1024
>>>>>
>>>>> #define MAX_OPTION_ROMS 16
>>>>> typedef struct QEMUOptionRom {
>>>>>
>>>>
>>>>
>>>
>>
>>
>
--
Alexey