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

["J. Hannken-Illjes" <hannken%mailbox.org@localhost>]

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

From: "J. Hannken-Illjes" <hannken%mailbox.org@localhost>
To: NetBSD GNATS <gnats-bugs%netbsd.org@localhost>
Cc: 
Subject: Re: kern/56329: nvme(4) takes long time to umount
Date: Mon, 25 Apr 2022 16:02:40 +0200

 With help from Paul Goyette I'm able to reproduce the behaviour here.
 
 - It is not related to nvme, it depends on the number of cached
   vnodes, 3456591 in the last run taking ~7 seconds.
 
 - With 64GByte memory my test machine takes ~6 seconds to unmount
   a file system with 3332133 cached vnodes with "ld at virtio".
 
 - This time to unmount didn't change in the last 7 years, testing
   kernels from October 2014, 2015 ... until now it always took 5 +- 1
   seconds to unmount.
 
 - Latest run took 5.864 seconds, 1.311 were spent in cache_purgevfs(),
   0.290 in VFS_SYNC() and 4.263 in vflush().
 
 To me this doesn't look like a regression and recycling ~570000 vnodes
 per second looks ok.
 
 --
 J. Hannken-Illjes - hannken%mailbox.org@localhost