linux-toradex.git/include/trace/events/rxrpc.h, branch v6.14

rxrpc: Fix the rxrpc_connection attend queue handling

2025-02-04T14:30:28+00:00

The rxrpc_connection attend queue is never used because conn::attend_link
is never initialised and so is always NULL'd out and thus always appears to
be busy.  This requires the following fix:

 (1) Fix this the attend queue problem by initialising conn::attend_link.

And, consequently, two further fixes for things masked by the above bug:

 (2) Fix rxrpc_input_conn_event() to handle being invoked with a NULL
     sk_buff pointer - something that can now happen with the above change.

 (3) Fix the RXRPC_SKB_MARK_SERVICE_CONN_SECURED message to carry a pointer
     to the connection and a ref on it.

Signed-off-by: David Howells 
cc: Marc Dionne 
cc: Jakub Kicinski 
cc: "David S. Miller" 
cc: Eric Dumazet 
cc: Paolo Abeni 
cc: Simon Horman 
cc: linux-afs@lists.infradead.org
cc: netdev@vger.kernel.org
Fixes: f2cce89a074e ("rxrpc: Implement a mechanism to send an event notification to a connection")
Link: https://patch.msgid.link/20250203110307.7265-3-dhowells@redhat.com
Signed-off-by: Paolo Abeni

rxrpc: Implement RACK/TLP to deal with transmission stalls [RFC8985]

2024-12-09T21:48:33+00:00

When an rxrpc call is in its transmission phase and is sending a lot of
packets, stalls occasionally occur that cause severe performance
degradation (eg. increasing the transmission time for a 256MiB payload from
0.7s to 2.5s over a 10G link).

rxrpc already implements TCP-style congestion control [RFC5681] and this
helps mitigate the effects, but occasionally we're missing a time event
that deals with a missing ACK, leading to a stall until the RTO expires.

Fix this by implementing RACK/TLP in rxrpc.

Signed-off-by: David Howells 
cc: Marc Dionne 
cc: linux-afs@lists.infradead.org
Signed-off-by: Jakub Kicinski

rxrpc: Manage RTT per-call rather than per-peer

2024-12-09T21:48:32+00:00

Manage the determination of RTT on a per-call (ie. per-RPC op) basis rather
than on a per-peer basis, averaging across all calls going to that peer.
The problem is that the RTT measurements from the initial packets on a call
may be off because the server may do some setting up (such as getting a
lock on a file) before accepting the rest of the data in the RPC and,
further, the RTT may be affected by server-side file operations, for
instance if a large amount of data is being written or read.

Note: When handling the FS.StoreData-type RPCs, for example, the server
uses the userStatus field in the header of ACK packets as supplementary
flow control to aid in managing this.  AF_RXRPC does not yet support this,
but it should be added.

Signed-off-by: David Howells 
cc: Marc Dionne 
cc: linux-afs@lists.infradead.org
Signed-off-by: Jakub Kicinski

rxrpc: Add a reason indicator to the tx_ack tracepoint

2024-12-09T21:48:32+00:00

Record the reason for the transmission of an ACK in the rxrpc_tx_ack
tracepoint, and not just in the rxrpc_propose_ack tracepoint.

Signed-off-by: David Howells 
cc: Marc Dionne 
cc: linux-afs@lists.infradead.org
Signed-off-by: Jakub Kicinski

rxrpc: Add a reason indicator to the tx_data tracepoint

2024-12-09T21:48:32+00:00

Add an indicator to the rxrpc_tx_data tracepoint to indicate what triggered
the transmission of a particular packet.  At this point, it's only normal
transmission and retransmission, plus the tracepoint is also used to record
loss injection, but in a future patch, TLP-induced (re-)transmission will
also be a thing.

Signed-off-by: David Howells 
cc: Marc Dionne 
cc: linux-afs@lists.infradead.org
Signed-off-by: Jakub Kicinski

rxrpc: Don't allocate a txbuf for an ACK transmission

2024-12-09T21:48:31+00:00

Don't allocate an rxrpc_txbuf struct for an ACK transmission.  There's now
no need as the memory to hold the ACK content is allocated with a page frag
allocator.  The allocation and freeing of a txbuf is just unnecessary
overhead.

Signed-off-by: David Howells 
cc: Marc Dionne 
cc: linux-afs@lists.infradead.org
Signed-off-by: Jakub Kicinski

rxrpc: Display userStatus in rxrpc_rx_ack trace

2024-12-09T21:48:30+00:00

Display the userStatus field from the Rx packet header in the rxrpc_rx_ack
trace line.  This is used for flow control purposes by FS.StoreData-type
kafs RPC calls.

Signed-off-by: David Howells 
cc: Marc Dionne 
cc: linux-afs@lists.infradead.org
Signed-off-by: Jakub Kicinski

rxrpc: Adjust the rxrpc_rtt_rx tracepoint

2024-12-09T21:48:30+00:00

Adjust the rxrpc_rtt_rx tracepoint in the following ways:

 (1) Display the collected RTT sample in the rxrpc_rtt_rx trace.

 (2) Move the division of srtt by 8 to the TP_printk() rather doing it
     before invoking the trace point.

 (3) Display the min_rtt value.

Signed-off-by: David Howells 
cc: Marc Dionne 
cc: linux-afs@lists.infradead.org
Signed-off-by: Jakub Kicinski

rxrpc: Store the DATA serial in the txqueue and use this in RTT calc

2024-12-09T21:48:29+00:00

Store the serial number set on a DATA packet at the point of transmission
in the rxrpc_txqueue struct and when an ACK is received, match the
reference number in the ACK by trawling the txqueue rather than sharing an
RTT table with ACK RTT.  This can be done as part of Tx queue rotation.

This means we have a lot more RTT samples available and is faster to search
with all the serial numbers packed together into a few cachelines rather
than being hung off different txbufs.

Signed-off-by: David Howells 
cc: Marc Dionne 
cc: linux-afs@lists.infradead.org
Link: https://patch.msgid.link/20241204074710.990092-25-dhowells@redhat.com
Signed-off-by: Jakub Kicinski

rxrpc: Use the new rxrpc_tx_queue struct to more efficiently process ACKs

2024-12-09T21:48:29+00:00

With the change in the structure of the transmission buffer to store
buffers in bunches of 32 or 64 (BITS_PER_LONG) we can place sets of
per-buffer flags into the rxrpc_tx_queue struct rather than storing them in
rxrpc_tx_buf, thereby vastly increasing efficiency when assessing the SACK
table in an ACK packet.

Signed-off-by: David Howells 
cc: Marc Dionne 
cc: linux-afs@lists.infradead.org
Link: https://patch.msgid.link/20241204074710.990092-24-dhowells@redhat.com
Signed-off-by: Jakub Kicinski