Re: kern/57503: nullfs locking contention

[mlelstv%serpens.de@localhost (Michael van Elst)]

The following reply was made to PR kern/57503; it has been noted by GNATS.

From: mlelstv%serpens.de@localhost (Michael van Elst)
To: gnats-bugs%netbsd.org@localhost
Cc: 
Subject: Re: kern/57503: nullfs locking contention
Date: Wed, 5 Jul 2023 11:27:32 -0000 (UTC)

 jperkin%pkgsrc.org@localhost writes:
 
 >mount_null(8) does not appear to scale very well. Attempting to use pkgsrc/pkgtools/mksandbox to create a single chroot and run pbulk scan processes inside it runs incredibly slowly.
 
 Works fine for me, although I recently had to adjust some mounts for performance reasons.
 
 A single builder looks like:
 
 procfs on /s1/proc type procfs (local)
 ptyfs on /s1/dev/pts type ptyfs (local)
 tmpfs on /s1/tmp type tmpfs (local)
 tmpfs on /s1/usr/pkg type tmpfs (local)
 /home/pbulk/pkgsrc-2023Q2 on /s1/usr/pkgsrc type null (read-only, local)
 /home/pbulk/amd64-10.0-2023Q2/pbulk/bulklog on /s1/pbulk/bulklog type null (local)
 /home/pbulk/amd64-10.0-2023Q2/pbulk/cache on /s1/pbulk/cache type null (local)
 tmpfs on /s1/pbulk/work type tmpfs (local)
 /scratch/pbulk/distfiles on /s1/pbulk/distfiles type null (local)
 /home/pbulk/packages-amd64-10.0-2023Q2 on /s1/pbulk/packages type null (local)
 /tank/data/pbulk/final-amd64-10.0-2023Q2 on /s1/pbulk/final type null (local)
 
 
 
 Previously I had only mounted /home/pbulk/amd64-10.0-2023Q2/pbulk -> /s1/pbulk
 which started to cause contention for /s1/pbulk/work. Avoiding the stacked
 mounts by mounting subdirectories of /s1/pbulk individually avoids this.