This is a note to let you know that I've just added the patch titled
net: sparx5: fix FDMA performance issue
to the 5.15-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
net-sparx5-fix-fdma-performance-issue.patch
and it can be found in the queue-5.15 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
commit 59838860ff6962c3b5864616b9e93af342a98329
Author: Daniel Machon <daniel.machon@xxxxxxxxxxxxx>
Date: Thu Dec 5 14:54:26 2024 +0100
net: sparx5: fix FDMA performance issue
[ Upstream commit f004f2e535e2b66ccbf5ac35f8eaadeac70ad7b7 ]
The FDMA handler is responsible for scheduling a NAPI poll, which will
eventually fetch RX packets from the FDMA queue. Currently, the FDMA
handler is run in a threaded context. For some reason, this kills
performance. Admittedly, I did not do a thorough investigation to see
exactly what causes the issue, however, I noticed that in the other
driver utilizing the same FDMA engine, we run the FDMA handler in hard
IRQ context.
Fix this performance issue, by running the FDMA handler in hard IRQ
context, not deferring any work to a thread.
Prior to this change, the RX UDP performance was:
Interval Transfer Bitrate Jitter
0.00-10.20 sec 44.6 MBytes 36.7 Mbits/sec 0.027 ms
After this change, the rx UDP performance is:
Interval Transfer Bitrate Jitter
0.00-9.12 sec 1.01 GBytes 953 Mbits/sec 0.020 ms
Fixes: 10615907e9b5 ("net: sparx5: switchdev: adding frame DMA functionality")
Signed-off-by: Daniel Machon <daniel.machon@xxxxxxxxxxxxx>
Signed-off-by: David S. Miller <davem@xxxxxxxxxxxxx>
Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>
diff --git a/drivers/net/ethernet/microchip/sparx5/sparx5_main.c b/drivers/net/ethernet/microchip/sparx5/sparx5_main.c
index 174d89ee6374..ccfad6fba5b4 100644
--- a/drivers/net/ethernet/microchip/sparx5/sparx5_main.c
+++ b/drivers/net/ethernet/microchip/sparx5/sparx5_main.c
@@ -647,12 +647,11 @@ static int sparx5_start(struct sparx5 *sparx5)
err = -ENXIO;
if (sparx5->fdma_irq >= 0) {
if (GCB_CHIP_ID_REV_ID_GET(sparx5->chip_id) > 0)
- err = devm_request_threaded_irq(sparx5->dev,
- sparx5->fdma_irq,
- NULL,
- sparx5_fdma_handler,
- IRQF_ONESHOT,
- "sparx5-fdma", sparx5);
+ err = devm_request_irq(sparx5->dev,
+ sparx5->fdma_irq,
+ sparx5_fdma_handler,
+ 0,
+ "sparx5-fdma", sparx5);
if (!err)
err = sparx5_fdma_start(sparx5);
if (err)
