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<base href="https://bugs.dpdk.org/">
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<body><table border="1" cellspacing="0" cellpadding="8" class="bz_new_table">
<tr>
<th>Bug ID</th>
<td><a class="bz_bug_link
bz_status_UNCONFIRMED "
title="UNCONFIRMED - MLX5 Windows : Issue with Packet Loss When Setting Descriptors Above 1<<14 on ConnectX6-DX"
href="https://bugs.dpdk.org/show_bug.cgi?id=1591">1591</a>
</td>
</tr>
<tr>
<th>Summary</th>
<td>MLX5 Windows : Issue with Packet Loss When Setting Descriptors Above 1<<14 on ConnectX6-DX
</td>
</tr>
<tr>
<th>Product</th>
<td>DPDK
</td>
</tr>
<tr>
<th>Version</th>
<td>24.11
</td>
</tr>
<tr>
<th>Hardware</th>
<td>x86
</td>
</tr>
<tr>
<th>OS</th>
<td>Windows
</td>
</tr>
<tr>
<th>Status</th>
<td>UNCONFIRMED
</td>
</tr>
<tr>
<th>Severity</th>
<td>normal
</td>
</tr>
<tr>
<th>Priority</th>
<td>Normal
</td>
</tr>
<tr>
<th>Component</th>
<td>ethdev
</td>
</tr>
<tr>
<th>Assignee</th>
<td>dev@dpdk.org
</td>
</tr>
<tr>
<th>Reporter</th>
<td>a.pollenus@deltacast.tv
</td>
</tr>
<tr>
<th>Target Milestone</th>
<td>---
</td>
</tr></table>
<p>
<div class="bz_comment_block">
<pre class="bz_comment_text">I am encountering an issue with the ConnectX6-DX on Windows. When I set the
number of descriptors to a value greater than 1<<14, all my packets are dropped
(imissed), except for the first one. The root cause is unclear, but I observed
that the maximum number of descriptors reported by rte_eth_dev_info_get() is
32768 (rx_desc_lim.nb_max), which I believe indicates that the number of
descriptors should be set to this value or lower.
Here are some test results using testpmd that demonstrate the issue:
TEST 1 : 4096 descriptors
./dpdk-testpmd -l 2-3 -n 4 -a 0000:03:00.0 --log-level=8
--log-level=pmd.common.mlx5:8 --log-level=pmd.net.mlx5:8 -- --socket-num=0
--burst=64 --txd=4096 --rxd=4096 --mbcache=512 --rxq=4 --txq=4 --nb-cores=1
--txpkts=1500 -i --forward-mode=rxonly --flow-isolate-all
testpmd> show port stats 0
######################## NIC statistics for port 0 ########################
RX-packets: 1626632 RX-missed: 0 RX-bytes: 2152490218
RX-errors: 0
RX-nombuf: 0
TX-packets: 0 TX-errors: 0 TX-bytes: 0
Throughput (since last show)
Rx-pps: 246876 Rx-bps: 2613496560
Tx-pps: 0 Tx-bps: 0
############################################################################
TEST 2 : 16384 descriptors
./dpdk-testpmd -l 2-3 -n 4 -a 0000:03:00.0 --log-level=8
--log-level=pmd.common.mlx5:8 --log-level=pmd.net.mlx5:8 -- --socket-num=0
--burst=64 --txd=4096 --rxd=16384 --mbcache=512 --rxq=4 --txq=4 --nb-cores=1
--txpkts=1500 -i --forward-mode=rxonly --flow-isolate-all
testpmd> show port stats 0
######################## NIC statistics for port 0 ########################
RX-packets: 2923021 RX-missed: 0 RX-bytes: 3867975188
RX-errors: 0
RX-nombuf: 0
TX-packets: 0 TX-errors: 0 TX-bytes: 0
Throughput (since last show)
Rx-pps: 246881 Rx-bps: 2613540240
Tx-pps: 0 Tx-bps: 0
############################################################################
TEST 3 : 20480 descriptors
./dpdk-testpmd -l 2-3 -n 4 -a 0000:03:00.0 --log-level=8
--log-level=pmd.common.mlx5:8 --log-level=pmd.net.mlx5:8 -- --socket-num=0
--burst=64 --txd=4096 --rxd=20480 --mbcache=512 --rxq=4 --txq=4 --nb-cores=1
--txpkts=1500 -i --forward-mode=rxonly --flow-isolate-all
testpmd> show port stats 0
######################## NIC statistics for port 0 ########################
RX-packets: 1 RX-missed: 2732098 RX-bytes: 1328
RX-errors: 0
RX-nombuf: 0
TX-packets: 0 TX-errors: 0 TX-bytes: 0
Throughput (since last show)
Rx-pps: 0 Rx-bps: 0
Tx-pps: 0 Tx-bps: 0
############################################################################
TEST 4 : 32768 descriptors
./dpdk-testpmd -l 2-3 -n 4 -a 0000:03:00.0 --log-level=8
--log-level=pmd.common.mlx5:8 --log-level=pmd.net.mlx5:8 -- --socket-num=0
--burst=64 --txd=4096 --rxd=32768 --mbcache=512 --rxq=4 --txq=4 --nb-cores=1
--txpkts=1500 -i --forward-mode=rxonly --flow-isolate-all
testpmd> show port stats 0
######################## NIC statistics for port 0 ########################
RX-packets: 1 RX-missed: 1129806 RX-bytes: 1328
RX-errors: 0
RX-nombuf: 0
TX-packets: 0 TX-errors: 0 TX-bytes: 0
Throughput (since last show)
Rx-pps: 0 Rx-bps: 0
Tx-pps: 0 Tx-bps: 0
############################################################################
I was able to reproduce this issue on versions 24.11 and 23.11, using DevX
version 24.10.26603.
Thank you in advance for your help,
Please let me know if you need further information.
Thank you.
</pre>
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