re: kern/56329: nvme(4) takes long time to umount

[matthew green <mrg%eterna.com.au@localhost>]

The following reply was made to PR kern/56329; it has been noted by GNATS.

From: matthew green <mrg%eterna.com.au@localhost>
To: gnats-bugs%netbsd.org@localhost, "J. Hannken-Illjes" <hannken%mailbox.org@localhost>
Cc: kern-bug-people%netbsd.org@localhost, gnats-admin%netbsd.org@localhost,
    netbsd-bugs%netbsd.org@localhost, paul%whooppee.com@localhost
Subject: re: kern/56329: nvme(4) takes long time to umount
Date: Thu, 21 Apr 2022 06:26:55 +1000

 >  Finally got a laptop with
 >      nvme0: SAMSUNG MZVLB256HAHQ-000L7, firmware 0L2QEXD7, serial S41GNB=
 0K593889
 >  and see unmount times of 10 .. 12 seconds with a DIAGNOSTIC + DEBUG + L=
 OCKDEBUG
 >  kernel.  All this time is spent in the first vflush().
 >  =
 
 >  On a GENERIC kernel without DIAGNOSTIC etc the unmount time goes down t=
 o less
 >  than a second and the disk becomes much faster.
 >  =
 
 >  What kind of kernel are/were you using?
 
 FWIW, i see this problem on non-nvme sometimes too, and it
 seems related to how much data was written between booting
 and shutdown.
 
 DIAGNOSTIC shouldn't affect speed nearly this much!  code
 like that should be in DEBUG probably.
 
 
 .mrg.