2 x quad-core system is slower that 2 x dual core on FreeBSD

[Kris Kennaway]

Alexey Popov wrote:
> Hi
> 
> Kris Kennaway wrote:
>> One more patch which may or may not help is:
>>
>>   http://www.freebsd.org/~jhb/patches/namei_rwlock.patch
>>
>> (may also require porting since it was against an older version of 
>> 7.0-CURRENT).  When I have tested this in the past it was a 
>> performance loss for reasons that I think I understand (basically, it 
>> is locally a performance improvement for the name cache but also 
>> requires a fixed lockmgr to avoid an overall performance loss), but I 
>> don't remember if I tested it in conjunction with the lockmgr patch.
> This patch doesn't apply to 7-STABLE because /sys/kern/vfs_cache.c was 
> changed significanly since rev. 1.108. I tried to patch it manually but 
> don't know what to do with cache_lookup() changes.

OK, I am about to go on vacation so I am not able to help with either of 
these things.

Kris

> 
>>>> There are patches you need to enable it on woodcrest.  They are in 
>>>> my p4 branch (kris-contention) but I don't have time right now to 
>>>> extract them.
>>> I think it would be very useful because I can't see any other ways to 
>>> profile FreeBSD on the modern many-cores machines.
>>
>> You can extract the changeset from my branch via 
>> http://perforce.freebsd.org.  Unfortunately I don't have time to do it 
>> myself.
> I'll try it if it does not also need porting.
> 
> With best regards,
> Alexey Popov
> 
>