Re: [CFT][RFC] HT scheduler

Nick Piggin
2003-12-11T13:30:31Z

William Lee Irwin III wrote:

>William Lee Irwin III wrote:
>
>>>If this thing is heavily threaded, it could be mm->page_table_lock.
>>>
>
>On Fri, Dec 12, 2003 at 12:09:04AM +1100, Nick Piggin wrote:
>
>>I'm not sure how threaded it is, probably very. Would inline spinlocks
>>help show up mm->page_table_lock?
>>It really looks like .text.lock.futex though, doesn't it? Would that be
>>the hashed futex locks? I wonder why it suddenly goes downhill past about
>>140 rooms though.
>>
>
>It will get contention anyway if they're all pounding on the same futex.
>OTOH, if they're all threads in the same process, they can hit other
>problems. I'll try to find out more about hackbench.
>

Oh, sorry I was talking about volanomark. hackbench AFAIK doesn't use
futexes at all, just pipes, and is not threaded at all, so it looks like
a different problem to the volanomark one.

hackbench runs into trouble at large numbers of tasks too though.