Hi Rajeev, Here are the results for 4.3.x branch: hpp@nid001293:/usr/projects/artab/users/hpp/osu-micro-benchmarks-5.8-mpich/mpi/pt2pt>srun --mpi=pmix -n 2 ./osu_latency # OSU MPI Latency Test v5.8 # Size Latency (us) 0 1.92 1 1.98 2 1.98 4 1.98 8 1.98 16 1.98 32 1.99 64 1.99 128 2.47 256 2.59 512 2.65 1024 2.76 2048 2.95 4096 3.00 8192 5.96 16384 6.64 32768 7.44 65536 8.75 131072 11.52 262144 17.08 524288 27.96 1048576 49.38 2097152 92.96 4194304 179.74 These are more like i would expect for SS11/OFI CXI provider. Howard Am Mi., 30. Juli 2025 um 12:48 Uhr schrieb Thakur, Rajeev <[email protected]>:

Hi Howard,

What was the latency with the 4.3.x branch?

Rajeev

*From: *Howard Pritchard via discuss <[email protected]> *Reply-To: *"[email protected]" <[email protected]> *Date: *Wednesday, July 30, 2025 at 1:43 PM *To: *"Zhou, Hui" <[email protected]> *Cc: *Howard Pritchard <[email protected]>, "[email protected]" < [email protected]> *Subject: *Re: [mpich-discuss] MPICH 5.0.1 performance on HPE SS11 plus more - a slurm problem

Hi Hui That didn’t help. I am not surprised though as our cluster is an NVIDIA free zone. What did help is to switch to the mpich 4. 3. x branch and latency results are nominal and the slurm problem went away too. So we will stick with that branch.

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Hi Hui

That didn’t help. I am not surprised though as our cluster is an NVIDIA free zone. What did help is to switch to the mpich 4.3.x branch and latency results are nominal and the slurm problem went away too. So we will stick with that branch.

Howard

On Mon, Jul 28, 2025 at 4:15 PM Zhou, Hui <[email protected]> wrote:

Hi Howard,

I wonder whether it is due to the overhead of querying pointer attributes. Could you try disable GPU support with `MPIR_CVAR_ENABLE_GPU=0` and see if the latency improves?

Hui ------------------------------

*From:* Howard Pritchard via discuss <[email protected]> *Sent:* Monday, July 28, 2025 9:41 AM *To:* [email protected] <[email protected]> *Cc:* Howard Pritchard <[email protected]> *Subject:* [mpich-discuss] MPICH 5.0.1 performance on HPE SS11 plus more - a slurm problem

Hi Folks, We are seeing a strange performance issue on our HPE SS11 system when testing osu_latency inter-node with MPICH. First the info: system using libfabric 1. 22. 0 slurm - 24. 11. 5 Here's my mpichversion output: MPICH Version: 5. 0. 0a1

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Hi Folks,

We are seeing a strange performance issue on our HPE SS11 system when testing osu_latency inter-node with MPICH.

First the info:

system using libfabric 1.22.0

slurm - 24.11.5

Here's my mpichversion output:

MPICH Version: 5.0.0a1

MPICH Release date: unreleased development copy

MPICH ABI: 0:0:0

MPICH Device: ch4:ofi

MPICH configure: --prefix=/XXXX/mpich_again/install --enable-g=no --enable-error-checking=no --with-device=ch4:ofi --enable-threads=multiple --with-ch4-shmmods=posix,xpmem --enable-thread-cs=per-vci --with-libfabric=/opt/cray/libfabric/1.22.0 --with-xpmem=/opt/cray/xpmem/default --with-pmix=/opt/pmix/gcc4x/5.0.8 --enable-fast=O3

MPICH CC: gcc -O3

MPICH CXX: g++ -O3

MPICH F77: gfortran -O3

MPICH FC: gfortran -O3

MPICH features: threadcomm

And here's the OSU latency results:

slurmstepd: error: mpi/pmix_v4: pmixp_coll_belong_chk: nid001439 [1]: pmixp_coll.c:280: No process controlled by this slurmstepd is involved in this collective.

slurmstepd: error: mpi/pmix_v4: _process_server_request: nid001439 [1]: pmixp_server.c:923: Unable to pmixp_state_coll_get()

slurmstepd: error: mpi/pmix_v4: pmixp_coll_ring_check: nid001438 [0]: pmixp_coll_ring.c:614: 0x15005c005dc0: unexpected contrib from nid001439:1, expected is 0

slurmstepd: error: mpi/pmix_v4: _process_server_request: nid001438 [0]: pmixp_server.c:937: 0x15005c005dc0: unexpected contrib from nid001439:1, coll->seq=0, seq=0

slurmstepd: error: mpi/pmix_v4: pmixp_coll_ring_reset_if_to: nid001438 [0]: pmixp_coll_ring.c:738: 0x1500580532f0: collective timeout seq=0

slurmstepd: error: mpi/pmix_v4: pmixp_coll_log: nid001438 [0]: pmixp_coll.c:286: Dumping collective state

slurmstepd: error: mpi/pmix_v4: pmixp_coll_ring_log: nid001438 [0]: pmixp_coll_ring.c:756: 0x1500580532f0: COLL_FENCE_RING state seq=0

slurmstepd: error: mpi/pmix_v4: pmixp_coll_ring_log: nid001438 [0]: pmixp_coll_ring.c:758: my peerid: 0:nid001438

slurmstepd: error: mpi/pmix_v4: pmixp_coll_ring_log: nid001438 [0]: pmixp_coll_ring.c:765: neighbor id: next 1:nid001439, prev 1:nid001439

slurmstepd: error: mpi/pmix_v4: pmixp_coll_ring_log: nid001438 [0]: pmixp_coll_ring.c:775: Context ptr=0x150058053368, #0, in-use=0

slurmstepd: error: mpi/pmix_v4: pmixp_coll_ring_log: nid001438 [0]: pmixp_coll_ring.c:775: Context ptr=0x1500580533a0, #1, in-use=0

slurmstepd: error: mpi/pmix_v4: pmixp_coll_ring_log: nid001438 [0]: pmixp_coll_ring.c:775: Context ptr=0x1500580533d8, #2, in-use=1

slurmstepd: error: mpi/pmix_v4: pmixp_coll_ring_log: nid001438 [0]: pmixp_coll_ring.c:786: seq=0 contribs: loc=1/prev=0/fwd=1

slurmstepd: error: mpi/pmix_v4: pmixp_coll_ring_log: nid001438 [0]: pmixp_coll_ring.c:788: neighbor contribs [2]:

slurmstepd: error: mpi/pmix_v4: pmixp_coll_ring_log: nid001438 [0]: pmixp_coll_ring.c:821: done contrib: -

slurmstepd: error: mpi/pmix_v4: pmixp_coll_ring_log: nid001438 [0]: pmixp_coll_ring.c:823: wait contrib: nid001439

slurmstepd: error: mpi/pmix_v4: pmixp_coll_ring_log: nid001438 [0]: pmixp_coll_ring.c:825: status=PMIXP_COLL_RING_PROGRESS

slurmstepd: error: mpi/pmix_v4: pmixp_coll_ring_log: nid001438 [0]: pmixp_coll_ring.c:829: buf (offset/size): 36/16384

slurmstepd: error: mpi/pmix_v4: pmixp_coll_ring_reset_if_to: nid001439 [1]: pmixp_coll_ring.c:738: 0x151d0c053400: collective timeout seq=0

slurmstepd: error: mpi/pmix_v4: pmixp_coll_log: nid001439 [1]: pmixp_coll.c:286: Dumping collective state

slurmstepd: error: mpi/pmix_v4: pmixp_coll_ring_log: nid001439 [1]: pmixp_coll_ring.c:756: 0x151d0c053400: COLL_FENCE_RING state seq=0

slurmstepd: error: mpi/pmix_v4: pmixp_coll_ring_log: nid001439 [1]: pmixp_coll_ring.c:758: my peerid: 1:nid001439

slurmstepd: error: mpi/pmix_v4: pmixp_coll_ring_log: nid001439 [1]: pmixp_coll_ring.c:765: neighbor id: next 0:nid001438, prev 0:nid001438

slurmstepd: error: mpi/pmix_v4: pmixp_coll_ring_log: nid001439 [1]: pmixp_coll_ring.c:775: Context ptr=0x151d0c053478, #0, in-use=0

slurmstepd: error: mpi/pmix_v4: pmixp_coll_ring_log: nid001439 [1]: pmixp_coll_ring.c:775: Context ptr=0x151d0c0534b0, #1, in-use=0

slurmstepd: error: mpi/pmix_v4: pmixp_coll_ring_log: nid001439 [1]: pmixp_coll_ring.c:775: Context ptr=0x151d0c0534e8, #2, in-use=1

slurmstepd: error: mpi/pmix_v4: pmixp_coll_ring_log: nid001439 [1]: pmixp_coll_ring.c:786: seq=0 contribs: loc=1/prev=0/fwd=1

slurmstepd: error: mpi/pmix_v4: pmixp_coll_ring_log: nid001439 [1]: pmixp_coll_ring.c:788: neighbor contribs [2]:

slurmstepd: error: mpi/pmix_v4: pmixp_coll_ring_log: nid001439 [1]: pmixp_coll_ring.c:821: done contrib: -

slurmstepd: error: mpi/pmix_v4: pmixp_coll_ring_log: nid001439 [1]: pmixp_coll_ring.c:823: wait contrib: nid001438

slurmstepd: error: mpi/pmix_v4: pmixp_coll_ring_log: nid001439 [1]: pmixp_coll_ring.c:825: status=PMIXP_COLL_RING_PROGRESS

slurmstepd: error: mpi/pmix_v4: pmixp_coll_ring_log: nid001439 [1]: pmixp_coll_ring.c:829: buf (offset/size): 36/16384

# OSU MPI Latency Test v5.8

# Size Latency (us)

0 1.66

1 9.29

2 9.57

4 9.69

8 9.76

16 9.77

32 9.76

64 9.77

128 10.32

256 7.54

512 7.45

1024 7.38

2048 7.37

4096 7.45

8192 9.21

16384 9.70

32768 10.63

65536 13.15

131072 16.96

262144 23.84

524288 36.16

1048576 60.36

2097152 108.43

4194304 228.31

Note the slurm behavior is - I launch the job. Go get coffee, do some duo-lingo, read some emails, then after about 10 minutes the osu latency runs.

I did not get the slurm problems using an older mpich 4.3.1 but did get the same performance issue. 9 usecs doesn't seem right for an 8-byte pingpong over libfabric S11. I was expecting more like 1.6 or so.

I am confident the slurm issue is unrelated to the latency issue.

Thanks for any suggestions on how to address either issue however.