[lustre-discuss] Lnet Self Test

[Andreas Dilger]

The first thing to note is that lst reports results in binary units
(MiB/s) while iperf reports results in decimal units (Gbps).  If you do the
conversion you get 2055.31 MiB/s = 2155 MB/s.

The other thing to check is the CPU usage. For TCP the CPU usage can
be high. You should try RoCE+o2iblnd instead.

Cheers, Andreas

On Nov 26, 2019, at 21:26, Pinkesh Valdria <pinkesh.valdria at oracle.com<mailto:pinkesh.valdria at oracle.com>> wrote:

Hello All,

I created a new Lustre cluster on CentOS7.6 and I am running lnet_selftest_wrapper.sh to measure throughput on the network.  The nodes are connected to each other using 25Gbps ethernet, so theoretical max is 25 Gbps * 125 = 3125 MB/s.    Using iperf3,  I get 22Gbps (2750 MB/s) between the nodes.


[root at lustre-client-2 ~]# for c in 1 2 4 8 12 16 20 24 ;  do echo $c ; ST=lst-output-$(date +%Y-%m-%d-%H:%M:%S)  CN=$c  SZ=1M  TM=30 BRW=write CKSUM=simple LFROM="10.0.3.7 at tcp1" LTO="10.0.3.6 at tcp1" /root/lnet_selftest_wrapper.sh; done ;

When I run lnet_selftest_wrapper.sh (from Lustre wiki<http://wiki.lustre.org/LNET_Selftest>) between 2 nodes,  I get a max of  2055.31  MiB/s,  Is that expected at the Lnet level?  Or can I further tune the network and OS kernel (tuning I applied are below) to get better throughput?



Result Snippet from lnet_selftest_wrapper.sh

[LNet Rates of lfrom]
[R] Avg: 4112     RPC/s Min: 4112     RPC/s Max: 4112     RPC/s
[W] Avg: 4112     RPC/s Min: 4112     RPC/s Max: 4112     RPC/s
[LNet Bandwidth of lfrom]
[R] Avg: 0.31     MiB/s Min: 0.31     MiB/s Max: 0.31     MiB/s
[W] Avg: 2055.30  MiB/s Min: 2055.30  MiB/s Max: 2055.30  MiB/s
[LNet Rates of lto]
[R] Avg: 4136     RPC/s Min: 4136     RPC/s Max: 4136     RPC/s
[W] Avg: 4136     RPC/s Min: 4136     RPC/s Max: 4136     RPC/s
[LNet Bandwidth of lto]
[R] Avg: 2055.31  MiB/s Min: 2055.31  MiB/s Max: 2055.31  MiB/s
[W] Avg: 0.32     MiB/s Min: 0.32     MiB/s Max: 0.32     MiB/s


Tuning applied:
Ethernet NICs:

ip link set dev ens3 mtu 9000

ethtool -G ens3 rx 2047 tx 2047 rx-jumbo 8191


less /etc/sysctl.conf
net.core.wmem_max=16777216
net.core.rmem_max=16777216
net.core.wmem_default=16777216
net.core.rmem_default=16777216
net.core.optmem_max=16777216
net.core.netdev_max_backlog=27000
kernel.sysrq=1
kernel.shmmax=18446744073692774399
net.core.somaxconn=8192
net.ipv4.tcp_adv_win_scale=2
net.ipv4.tcp_low_latency=1
net.ipv4.tcp_rmem = 212992 87380 16777216
net.ipv4.tcp_sack = 1
net.ipv4.tcp_timestamps = 1
net.ipv4.tcp_window_scaling = 1
net.ipv4.tcp_wmem = 212992 65536 16777216
vm.min_free_kbytes = 65536
net.ipv4.tcp_congestion_control = cubic
net.ipv4.tcp_timestamps = 0
net.ipv4.tcp_congestion_control = htcp
net.ipv4.tcp_no_metrics_save = 0



echo "#
# tuned configuration
#
[main]
summary=Broadly applicable tuning that provides excellent performance across a variety of common server workloads

[disk]
devices=!dm-*, !sda1, !sda2, !sda3
readahead=>4096

[cpu]
force_latency=1
governor=performance
energy_perf_bias=performance
min_perf_pct=100
[vm]
transparent_huge_pages=never
[sysctl]
kernel.sched_min_granularity_ns = 10000000
kernel.sched_wakeup_granularity_ns = 15000000
vm.dirty_ratio = 30
vm.dirty_background_ratio = 10
vm.swappiness=30
" > lustre-performance/tuned.conf

tuned-adm profile lustre-performance


Thanks,
Pinkesh Valdria

_______________________________________________
lustre-discuss mailing list
lustre-discuss at lists.lustre.org<mailto:lustre-discuss at lists.lustre.org>
http://lists.lustre.org/listinfo.cgi/lustre-discuss-lustre.org
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://lists.lustre.org/pipermail/lustre-discuss-lustre.org/attachments/20191127/9b660c12/attachment-0001.html>