From: Josh Triplett <josh@joshtriplett.org>

Date: Fri, 28 Feb 2020 18:52:28 -0800

Subject: [PATCH] nvme: Check for readiness more quickly, to speed up boot time

Git-commit: 3e98c2443f5c7f127b5b7492a3089e92a1c85112

Patch-mainline: v5.7-rc1

References: bsc#1161930

After initialization, nvme_wait_ready checks for readiness every 100ms,

even though the drive may be ready far sooner than that. This delays

system boot by hundreds of milliseconds. Reduce the delay, checking for

readiness every millisecond instead.

Boot-time tests on an AWS c5.12xlarge:

Before:

[    0.546936] initcall nvme_init+0x0/0x5b returned 0 after 37 usecs

...

[    0.764178] nvme nvme0: 2/0/0 default/read/poll queues

[    0.768424]  nvme0n1: p1

[    0.774132] EXT4-fs (nvme0n1p1): mounted filesystem with ordered data mode. Opts: (null)

[    0.774146] VFS: Mounted root (ext4 filesystem) on device 259:1.

...

[    0.788141] Run /sbin/init as init process

After:

[    0.537088] initcall nvme_init+0x0/0x5b returned 0 after 37 usecs

...

[    0.543457] nvme nvme0: 2/0/0 default/read/poll queues

[    0.548473]  nvme0n1: p1

[    0.554339] EXT4-fs (nvme0n1p1): mounted filesystem with ordered data mode. Opts: (null)

[    0.554344] VFS: Mounted root (ext4 filesystem) on device 259:1.

...

[    0.567931] Run /sbin/init as init process

Signed-off-by: Josh Triplett <josh@joshtriplett.org>

Reviewed-by: Sagi Grimberg <sagi@grimberg.me>

Reviewed-by: Chaitanya Kulkarni <chaitanya.kulkarni@wdc.com>

Signed-off-by: Keith Busch <kbusch@kernel.org>

Acked-by: Hannes Reinecke <hare@suse.com>

---

 drivers/nvme/host/core.c | 2 +-

 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/nvme/host/core.c b/drivers/nvme/host/core.c

index c9988942d0aa..0e38e07a302f 100644

--- a/drivers/nvme/host/core.c

+++ b/drivers/nvme/host/core.c

@@ -2078,7 +2078,7 @@ static int nvme_wait_ready(struct nvme_ctrl *ctrl, u64 cap, bool enabled)

 		if ((csts & NVME_CSTS_RDY) == bit)

 			break;

-		msleep(100);

+		usleep_range(1000, 2000);

 		if (fatal_signal_pending(current))

 			return -EINTR;

 		if (time_after(jiffies, timeout)) {

-- 

2.16.4