[mvapich-discuss] RDMA FAST PATH

[Hari Subramoni]

Hello,

As the userguide suggests, the environment variable to use to is "
MV2_RDMA_USE_FAST_PATH=0".

http://mvapich.cse.ohio-state.edu/static/media/mvapich/mvapich2-2.2rc1-userguide.html#x1-24600011.86

You should be seeing slight differences in latency - 2% to 7%. You should
see bigger differences in bandwidth (osu_bw), message rate (osu_mbw_mr) and
bidirectional bandwidth (osu_bibw).

Thx,
Hari.

On Thu, Apr 21, 2016 at 2:14 PM, Hoang-Vu Dang <dang.hvu at gmail.com> wrote:

> I'm testing mvapich2 version 2.1 with and without fast-path but I do not
> see any different in performance.
>
> The document said the environment variable is MV2_RDMA_USE_FAST_PATH
>
> I set it to 0 and the performance remains identify (osu_latency).
>
> On the other hand, when I set the MV2_RDMA_FAST_PATH_BUF_SIZE=0 I got an
> error:
>
> src/mpid/ch3/channels/mrail/src/gen2/ibv_priv.c at line 118:
> (rdma_fp_buffer_size * num_rdma_buffer)>0
>
> When I set MV2_RDMA_FAST_PATH_BUF_SIZE=16 it works but performance is
> slower significantly.
>
> My question is, what is the proper way to disable RDMA FAST PATH and use
> the send/recv eager protocol ?
>
> Vu
>
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