Re: [OMPI devel] Infiniband memory usage with XRC

2010-05-23 Thread Pavel Shamis (Pasha)
~ 2300 KB - is it difference per machine or per MPI process ? In OMPI XRC mode we allocate some additional resources that may consume some memory (the hash table), but even so ~2M sounds too much for me. When I will have time I will try to calculate the "resonable" difference. Pasha Sylvain J

Re: [OMPI devel] Infiniband memory usage with XRC

2010-05-19 Thread Sylvain Jeaugey
On Mon, 17 May 2010, Pavel Shamis (Pasha) wrote: Sylvain Jeaugey wrote: The XRC protocol seems to create shared receive queues, which is a good thing. However, comparing memory used by an "X" queue versus and "S" queue, we can see a large difference. Digging a bit into the code, we found some

Re: [OMPI devel] Infiniband memory usage with XRC

2010-05-17 Thread Pavel Shamis (Pasha)
Sylvain Jeaugey wrote: The XRC protocol seems to create shared receive queues, which is a good thing. However, comparing memory used by an "X" queue versus and "S" queue, we can see a large difference. Digging a bit into the code, we found some So, do you see that X consumes more that S ? This

Re: [OMPI devel] Infiniband memory usage with XRC

2010-05-17 Thread Sylvain Jeaugey
Thanks Pasha for these details. On Mon, 17 May 2010, Pavel Shamis (Pasha) wrote: blocking is the receive queues, because they are created during MPI_Init, so in a way, they are the "basic fare" of MPI. BTW SRQ resources are also allocated on demand. We start with very small SRQ and it is incre

Re: [OMPI devel] Infiniband memory usage with XRC

2010-05-17 Thread Pavel Shamis (Pasha)
Please see below. When using XRC queues, Open MPI is indeed creating only one XRC queue per node (instead of per-host). The problem is that the number of send elements in this queue is multiplied by the number of processes on the remote host. So, what are we getting from this ? Not much, e

[OMPI devel] Infiniband memory usage with XRC

2010-05-17 Thread Sylvain Jeaugey
Hi list, We did some testing on memory taken by Infiniband queues in Open MPI using the XRC protocol, which is supposed to reduce the needed memory for Infiniband connections. When using XRC queues, Open MPI is indeed creating only one XRC queue per node (instead of per-host). The problem is