[knem-devel] "unexisting region cookie" error

bin Wang bighead521 at gmail.com
Tue Jul 12 17:20:08 CEST 2011

hello Brice,

one more question.

What's the max memory size that could be registered into KNEM kernel
module? I didn't find any info on the webpage, so I assume that
there is no limitation. As long as userspace application can get 
memory allocation from OS successfully, KNEM is able to register
it for RDMA.

Besides, KNEM just registers the memory addresses, not the contents 
in the memory buffer, which means that once a reading process gets a
multiple-use cookie, it could always read from that buffer even if 
the buffer has already been updated after registration. I should
guarantee in my own code that the buffer should not be updated before 
its data has been copied by some other reading processes.
Is my understanding correct?



Wang Bin
Bighead actually means big stomach and huge brain, 
and Bighead will definitely be a big name in the coming future.

On Tue, 2011-07-12 at 07:13 +0200, Brice Goglin wrote:
> Actually, each process can even open /dev/knem multiple times and
> register 2^31 cookies in each of them. So you will reach the system
> memory limit before you reach the knem limits :)

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