5.15-stable review patch. If anyone has any objections, please let me know.
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From: Daniel Machon daniel.machon@microchip.com
[ 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@microchip.com Signed-off-by: David S. Miller davem@davemloft.net Signed-off-by: Sasha Levin sashal@kernel.org --- drivers/net/ethernet/microchip/sparx5/sparx5_main.c | 11 +++++------ 1 file changed, 5 insertions(+), 6 deletions(-)
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)