On Fri, Nov 22, 2024 at 6:04 AM Christoph Hellwig <hch@xxxxxx> wrote:
>
> On Thu, Nov 21, 2024 at 11:04:19PM -0600, Sam Protsenko wrote:
> > Hi Christoph,
> >
> > This patch causes a regression on E850-96 board. Specifically, there are
> > two noticeable time lags when booting Debian rootfs:
>
> What storage driver does this board use? Anything else interesting
> about the setup?
>
It's an Exynos based board with eMMC, so it uses DW MMC driver, with
Exynos glue layer on top of it, so:
drivers/mmc/host/dw_mmc.c
drivers/mmc/host/dw_mmc-exynos.c
I'm using the regular ARM64 defconfig. Nothing fancy about this setup
neither, the device tree with eMMC definition (mmc_0) is here:
arch/arm64/boot/dts/exynos/exynos850-e850-96.dts
FWIW, I was able to narrow down the issue to dd_insert_request()
function. With this hack the freeze is gone:
8<-------------------------------------------------------------------->8
diff --git a/block/mq-deadline.c b/block/mq-deadline.c
index acdc28756d9d..83d272b66e71 100644
--- a/block/mq-deadline.c
+++ b/block/mq-deadline.c
@@ -676,7 +676,7 @@ static void dd_insert_request(struct blk_mq_hw_ctx
*hctx, struct request *rq,
struct request_queue *q = hctx->queue;
struct deadline_data *dd = q->elevator->elevator_data;
const enum dd_data_dir data_dir = rq_data_dir(rq);
- u16 ioprio = req_get_ioprio(rq);
+ u16 ioprio = 0; /* the same as old req->ioprio */
u8 ioprio_class = IOPRIO_PRIO_CLASS(ioprio);
struct dd_per_prio *per_prio;
enum dd_prio prio;
8<-------------------------------------------------------------------->8
Does it tell you anything about where the possible issue can be?
Thanks!
