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Subject: Re: [OMPI users] Excessive Use of CPU System Resources with OpenMPI 1.2.4 using TCP only ..
From: Terry Frankcombe (terry_at_[hidden])
Date: 2008-01-22 00:54:56


Well, I have noticed that when a process is waiting for communication
from another process the reported CPU usage remains around 100%. Is
that what you mean? I haven't explored whether these processes give way
to other active processes under the linux scheduler, nor whether I
should expect anything different. This has been with 1.2.3 and 1.2.4.

On Tue, 2008-01-22 at 16:48 +1100, Graham Jenkins wrote:
> We've observed an excessive use of CPU system resources with OpenMPI
> 1.2.4 using TCP connections only on our SL5 x86_64 Cluster. Typically,
> for a simple Canonical Ring Program, we're seeing between 30 and 70%
> system usage.
>
> Has anybody else noticed this sort of behaviour?
> And does anybody have some suggestions for resolving the issue?
>
> Present values we have are:
> --
> ompi_info --param btl tcp |grep MCA
> MCA btl: parameter "btl_base_debug" (current value: "0")
> MCA btl: parameter "btl" (current value: <none>)
> MCA btl: parameter "btl_base_verbose" (current value: "0")
> MCA btl: parameter "btl_tcp_if_include" (current value:
> "eth0")
> MCA btl: parameter "btl_tcp_if_exclude" (current value:
> "lo")
> MCA btl: parameter "btl_tcp_free_list_num" (current
> value: "8")
> MCA btl: parameter "btl_tcp_free_list_max" (current
> value: "-1")
> MCA btl: parameter "btl_tcp_free_list_inc" (current
> value: "32")
> MCA btl: parameter "btl_tcp_sndbuf" (current value:
> "131072")
> MCA btl: parameter "btl_tcp_rcvbuf" (current value:
> "131072")
> MCA btl: parameter "btl_tcp_endpoint_cache" (current
> value: "30720")
> MCA btl: parameter "btl_tcp_exclusivity" (current
> value: "0")
> MCA btl: parameter "btl_tcp_eager_limit" (current
> value: "65536")
> MCA btl: parameter "btl_tcp_min_send_size" (current
> value: "65536")
> MCA btl: parameter "btl_tcp_max_send_size" (current
> value: "131072")
> MCA btl: parameter "btl_tcp_min_rdma_size" (current
> value: "131072")
> MCA btl: parameter "btl_tcp_max_rdma_size" (current
> value: "2147483647")
> MCA btl: parameter "btl_tcp_flags" (current value: "122")
> MCA btl: parameter "btl_tcp_priority" (current value: "0")
> MCA btl: parameter "btl_base_warn_component_unused"
> (current value: "1")
>