net/mlx5 Tx stuck if mbuf has too many segments
https://bugs.dpdk.org/show_bug.cgi?id=1367
Bug ID: 1367
Summary: net/mlx5 Tx stuck if mbuf has too many segments
Product: DPDK
Version: 23.11
Hardware: All
OS: All
Status: UNCONFIRMED
Severity: normal
Priority: Normal
Component: ethdev
Assignee: [email protected]
Reporter: [email protected]Target Milestone: ---
net/mlx5 Tx stuck if mbuf has too many segments
net/mlx5 reports maximum number of Tx segments in device info, but it does not check it on Tx prepare and simply do not send it on Tx burst.
As the result if such packet is encountered, app does not know (without extra efforts) why it fails to send the packet after successful Tx prepare. In theory the reason could be fully occupied Tx queue and application should simply retry forever.
Found by test run at UNH IOL:
1. Test checks reported maximum segments count: tx_desc_lim.nb_mtu_seg_max=40
https://ts-factory.io/bublik/v2/log/477842?focusId=479564&mode=treeAndinfoAndlog&experimental=true&lineNumber=1_25
2. Test splits the packet into 60 segments:
https://ts-factory.io/bublik/v2/log/477842?focusId=479564&mode=treeAndinfoAndlog&experimental=true&lineNumber=1_49
3. Test logs expectations for the packet to be rejected by Tx prepare:
https://ts-factory.io/bublik/v2/log/477842?focusId=479564&mode=treeAndinfoAndlog&experimental=true&lineNumber=1_60
4. Tx prepare accepts the packet and the test logs error:
https://ts-factory.io/bublik/v2/log/477842?focusId=479564&mode=treeAndinfoAndlog&experimental=true&lineNumber=1_62
5. Test tries to Tx burst the packet, but it returns 0. One more error is logged.
https://ts-factory.io/bublik/v2/log/477842?focusId=479564&mode=treeAndinfoAndlog&experimental=true&lineNumber=1_62
IMHO better behaviour here would be to accept the packet bug simply drop it in SW on Tx before passing to HW. Just avoid Tx stuck.
Of course Tx prepare should reject the packet at step 4.
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http://bugs.dpdk.org/show_bug.cgi?id=1367
[email protected] ([email protected]) changed:
What |Removed |Added
----------------------------------------------------------------------------
Status|UNCONFIRMED |RESOLVED
Resolution|--- |FIXED
CC| |[email protected]--- Comment #6 from [email protected] ([email protected]) --- Closing as the discussion ended.
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