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SubjectRe: [PATCH] fs/proc: Move kfree outside pde_unload_lock
On 08/24/2012 09:58 AM, Eric Dumazet wrote:
> Le vendredi 24 août 2012 à 09:48 -0500, Nathan Zimmer a écrit :
>> On Wed, Aug 22, 2012 at 11:42:58PM +0200, Eric Dumazet wrote:
>>> On Wed, 2012-08-22 at 20:28 +0200, Eric Dumazet wrote:
>>>
>>>> Thats interesting, but if you really want this to fly, one RCU
>>>> conversion would be much better ;)
>>>>
>>>> pde_users would be an atomic_t and you would avoid the spinlock
>>>> contention.
>>> Here is what I had in mind, I would be interested to know how it helps a 512 core machine ;)
>>>
>> Here are the results and they look great.
>>
>> cpuinfo baseline moved kfree Rcu
>> tasks read-sec read-sec read-sec
>> 1 0.0141 0.0141 0.0141
>> 2 0.0140 0.0140 0.0142
>> 4 0.0140 0.0141 0.0141
>> 8 0.0145 0.0145 0.0140
>> 16 0.0553 0.0548 0.0168
>> 32 0.1688 0.1622 0.0549
>> 64 0.5017 0.3856 0.1690
>> 128 1.7005 0.9710 0.5038
>> 256 5.2513 2.6519 2.0804
>> 512 8.0529 6.2976 3.0162
>>
>>
>>
> Indeed...
>
> Could you explicit the test you are actually doing ?
>
> Thanks
>
>


It is a dead simple test.
The test starts by forking off X number of tasks
assigning each their own cpu.
Each task then allocs a bit of memory.
All tasks wait on a memory cell for the go order.
We measure the read time starting here.
Once the go order is given they all read a chunk of the selected proc file.
I was using /proc/cpuinfo to test.
Once everyone has finished we take the end read time.




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