[PATCH v2 3/4] soc: apple: rtkit: Use high prio work queue

Sven Peter via B4 Relay
2025-02-26T19:00:16Z

From: Janne Grunau <j@jannau.net>

rtkit messages as communication with the DCP firmware for framebuffer
swaps or input events are time critical so use WQ_HIGHPRI to prevent
user space CPU load to increase latency.
With kwin_wayland 6's explicit sync mode user space load was able to
delay the IOMFB rtkit communication enough to miss vsync for surface
swaps. Minimal test scenario is constantly resizing a glxgears
Xwayland window.

Signed-off-by: Janne Grunau <j@jannau.net>
Reviewed-by: Alyssa Rosenzweig <alyssa@rosenzweig.io>
Signed-off-by: Sven Peter <sven@svenpeter.dev>
---
drivers/soc/apple/rtkit.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/soc/apple/rtkit.c b/drivers/soc/apple/rtkit.c
index 7e7b4f64ab17..4b78463dd5a1 100644
--- a/drivers/soc/apple/rtkit.c
+++ b/drivers/soc/apple/rtkit.c
@@ -696,7 +696,7 @@ struct apple_rtkit *apple_rtkit_init(struct device *dev, void *cookie,
rtk->mbox->rx = apple_rtkit_rx;
rtk->mbox->cookie = rtk;

- rtk->wq = alloc_ordered_workqueue("rtkit-%s", WQ_MEM_RECLAIM,
+ rtk->wq = alloc_ordered_workqueue("rtkit-%s", WQ_HIGHPRI | WQ_MEM_RECLAIM,
dev_name(rtk->dev));
if (!rtk->wq) {
ret = -ENOMEM;

--
2.34.1