New SCHED_SMP diff.

[Jeff Roberson]

On Mon, 2 Jul 2007, Thomas Sparrevohn wrote:

> On Monday 02 July 2007 17:50:44 Abdullah Ibn Hamad Al-Marri wrote:
>> On 7/2/07, Jeff Roberson <jroberson at chesapeake.net> wrote:
>>> I fixed a major bug in SCHED_SMP that impacted some users causing bad
>>> performance and invalid load counts.  Attilio also added support for i386
>>> based machines.  I have tested on UP which works although INVARIANTS and
>>> WITNESS don't work properly on UP kernels.  Single processor SMP kernels
>>> work fine.
>>>
>>> This diff also includes another patch that I intend to commit to current
>>> which significantly improved write performance for mysql by removing
>>> all use of Giant in fcntl().
>>>
>>> Please report any stability or performance problems with this patch.  The
>>> more positive reports I get the more likely it will go into 7.0.
>>>
>>> Thanks,
>>> Jeff
>>
>> Jeff,
>>
>> This makes my Intel C2D E6660 get really busy, and MySQL 5.0.41 from
>> ports run faster :)
>>
>> Thanks for making such great SCHED, when will you make it in the tree? :)
>>
>
> Hmm - Weird it gives negative results on my C2D XQ6700 - I ran four
> tests using "make world" benchmark - I am using ZFS for all filesystems
> except root - however I would not think that matters - I tested with "-j 8"
> and "-j 4" but it did not change the overall result
>

Hi, can you try sysctl kern.sched.steal_busy=1?  Please tell me if that 
improves things.  This will resolve short-term load imbalances by stealing 
threads from other processors.

Thanks,
Jeff

>
> SCHED_SMP - rm -rf /usr/obj/* && /usr/bin/time -l make -j 4 buildworld
>
> 1272.53 real      2482.83 user       945.08 sys
> 1268.45 real      2483.46 user       950.95 sys
> 1274.19 real      2481.91 user       953.19 sys
> 1292.27 real      2482.59 user       957.37 sys
>
>   2423814  voluntary context switches
>    885934  involuntary context switches
>
>
> SCHED_4BSD - rm -rf /usr/obj/* && /usr/bin/time -l make -j 4 buildworld
>
> 1125.28 real      2675.17 user      1055.18 sys
> 1124.74 real      2684.95 user      1057.64 sys
> 1123.76 real      2678.64 user      1061.89 sys
> 1120.68 real      2676.78 user      1061.03 sys
>
>
>   2587885  voluntary context switches
>    708274  involuntary context switches
>
>
>
>
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