Re: kern/57199: Pure PVH i386 guests hang on disk activity

[Brad Spencer <brad%anduin.eldar.org@localhost>]

The following reply was made to PR kern/57199; it has been noted by GNATS.

From: Brad Spencer <brad%anduin.eldar.org@localhost>
To: gnats-bugs%netbsd.org@localhost
Cc: kern-bug-people%netbsd.org@localhost, gnats-admin%netbsd.org@localhost, netbsd-bugs%netbsd.org@localhost,
        gdt%lexort.com@localhost
Subject: Re: kern/57199: Pure PVH i386 guests hang on disk activity
Date: Fri, 12 Jul 2024 13:17:50 -0400

 This is still 100% reproducable in 10.0 built from source as of
 2024-03-28.
 
 Config file:
 kernel = "/lhome/xen/kernels/NetBSD_10.x/NetBSD_10_branch_20240328/i386/netbsd-GENERIC"
 memory = 512
 cpu_weight = 32
 name = "nbsd10test32bit"
 type="pvh"
 vcpus = 1
 vif = [ 'mac=aa:00:00:50:07:f4, bridge=bridge4' ]
 disk = [ 'phy:/dev/mapper/rustvg0-nbsd10test32bitlv0,0x01,w' ]
 root = "xbd0"
 
 
 nbsd10test32bit# uname -a
 NetBSD nbsd10test32bit 10.0 NetBSD 10.0 (GENERIC) #0: Sat Mar 30 22:01:46 EDT 2024  brad%samwise.nat.eldar.org@localhost:/lhome/NetBSD_10_branch_20240328/i386/OBJ/sys/arch/i386/compile/GENERIC i386
 
 Create a tar archive that is fairly big.  It is likely that the larger
 sets will work, but what I used was a tar archive from the userland of
 the system itself (something like: cd /;tar -cf /var/tmp/distball.tar
 ./bin ./lib ./sbin ./usr ./stand).  I placed this in /var/tmp and called
 it distball.tar
 
 Create a directory in the path /var/tmp/Q and cd there.
 
 Untar the archive..  something like:  tar -xvpf ../distball.tar
 
 The untar will work for a short time and then hang up.  A CTRL-T
 produces this:
 x ./usr/libexec/cc1obj[ 115.0723697] load: 0.15  cmd: tar 1854 [uvnfp2] 0.04u 0.14s 0% 5340k
 [ 116.9523882] load: 0.13  cmd: tar 1854 [uvnfp2] 0.04u 0.14s 0% 5340k
 [ 118.0724972] load: 0.13  cmd: tar 1854 [uvnfp2] 0.04u 0.14s 0% 5340k
 [ 118.6725079] load: 0.13  cmd: tar 1854 [uvnfp2] 0.04u 0.14s 0% 5340k
 
 
 If I ran the same test with 1GB of memory it get a little further along,
 but still hangs up:
 x ./usr/libexec/postfix/scache[  66.3212543] load: 0.34  cmd: tar 1977 [biowait] 0.04u 0.20s 0% 5344k
 [  67.1712694] load: 0.34  cmd: tar 1977 [biowait] 0.04u 0.20s 0% 5344k
 [  67.3612609] load: 0.34  cmd: tar 1977 [biowait] 0.04u 0.20s 0% 5344k
 [  68.2412022] load: 0.34  cmd: tar 1977 [biowait] 0.04u 0.20s 0% 5344k
 [  68.4512385] load: 0.34  cmd: tar 1977 [biowait] 0.04u 0.20s 0% 5344k
 [  68.6312665] load: 0.34  cmd: tar 1977 [biowait] 0.04u 0.20s 0% 5344k
 [  68.8012961] load: 0.34  cmd: tar 1977 [biowait] 0.04u 0.20s 0% 5344k
 [  68.9713106] load: 0.34  cmd: tar 1977 [biowait] 0.04u 0.20s 0% 5344k
 [  69.1213030] load: 0.34  cmd: tar 1977 [biowait] 0.04u 0.20s 0% 5344k
 
 
 When the system is hung up, trying to log into the console will stick
 after entering the username.  You can get into ddb from the console.
 
 A PV+PVSHIM kernel of the same generation of source will work just fine
 with the same test.