nvme: Check for readiness more quickly, to speed up boot time

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>

diff --git a/drivers/nvme/host/core.c b/drivers/nvme/host/core.c
index c998894..0e38e07 100644 (file)
--- 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)) {