Ingo Molnar wrote:
> * Peter Zijlstra wrote:
>
>
>> * WOW *
>>
>
> WOW indeed - and i can see a similar _brutal_ speedup on two separate
> 16-way boxes as well:
>
> 16 CPUs, running 128 parallel test-tasks.
>
> NO_OWNER_SPIN:
> avg ops/sec: 281595
>
> OWNER_SPIN:
>
Steven Rostedt wrote:
> On Wed, 7 Jan 2009, Gregory Haskins wrote:
>
>> In my defense, the -rt versions of the patches guarantee this is ok
>> based on a little hack:
>>
>
> The -rt versions worry about much more than what the mutex code in
> mainl
[resend: restore CC list]
>>> Linus Torvalds 01/07/09 6:33 PM >>>
>On Wed, 7 Jan 2009, Steven Rostedt wrote:
>>
>> What would be interesting is various benchmarks against all three.
>>
>> 1) no mutex spinning.
>> 2) get_task_struct() implementation.
>> 3) spin_or_sched implementation.
>
>One of
[resend: i fat fingered the reply-to-all for a few messages]
>>> Linus Torvalds 01/07/09 6:20 PM >>>
>On Wed, 7 Jan 2009, Linus Torvalds wrote:
>> >
>> > "Is get_task_struct() really that bad?"
>>
>> Yes. It's an atomic access (two, in fact, since you need to release it
>> too), which is a huge
Hi Ingo,
Ingo Molnar wrote:
> * Gregory Haskins wrote:
>
>
>> Can I ask a simple question in light of all this discussion?
>>
>> "Is get_task_struct() really that bad?"
>>
>
> it dirties a cacheline and it also involves atomics.
>
Andi Kleen wrote:
>> I appreciate this is sample code, but using __get_user() on
>> non-userspace pointers messes up architectures which have separate
>> user/kernel spaces (eg the old 4G/4G split for x86-32). Do we have an
>> appropriate function for kernel space pointers?
>>
>
> probe_kern
Peter Zijlstra wrote:
> On Tue, 2009-01-06 at 14:16 +0100, Ingo Molnar wrote:
>
>> * Gregory Haskins wrote:
>>
>>
>>> Ingo Molnar wrote:
>>>
>>>> There's no time or spin-rate based heuristics in this
Ingo Molnar wrote:
> There's no time or spin-rate based heuristics in this at all (i.e. these
> mutexes are not 'adaptive' at all!),
FYI: The original "adaptive" name was chosen in the -rt implementation
to reflect that the locks can adaptively spin or sleep, depending on
conditions. I realize t
