Re: kern/55268: tmpfs is slow

[Joerg Sonnenberger <joerg%bec.de@localhost>]

The following reply was made to PR kern/55268; it has been noted by GNATS.

From: Joerg Sonnenberger <joerg%bec.de@localhost>
To: gnats-bugs%netbsd.org@localhost
Cc: 
Subject: Re: kern/55268: tmpfs is slow
Date: Fri, 15 May 2020 18:29:47 +0200

 On Fri, May 15, 2020 at 03:55:00PM +0000, Andreas Gustafsson wrote:
 > Doing a "build.sh -j 24 release" on a tmpfs takes more real time than
 > on an ffs mounted with "-o async", and uses much more system time.
 
 Careful with DIAGNOSTIC as it increases vnode lock contention quite a
 bit. Don't have the performance numbers for the bulk build anymore, but
 it is quite visible. Otherwise, this greatly suggests some form of lock
 contention or another, so lockstat output would be the most useful thing
 (e.g. lockstat -b 999999 build.sh ...). This doesn't reflect my
 experience at the very least, but lock contention can be somewhat
 catastrophic and small changes can have dramatic impact. That said, in
 the current form the bug report is not really useful.
 
 Joerg