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Date:      Wed, 7 Nov 2007 08:46:35 +0100
From:      Martijn Plak <martijn@plak.net>
To:        freebsd-fs@freebsd.org
Subject:   Re: ZFS kmem_map too small.
Message-ID:  <5ED261E6-A85A-4D7D-A01A-4688802FECB9@plak.net>
In-Reply-To: <20071106125552.GO5268@garage.freebsd.pl>
References:  <20071005000046.GC92272@garage.freebsd.pl> <20071008121523.GM2327@garage.freebsd.pl> <20071105215035.GC26730@heff.fud.org.nz> <2e77fc10711051531k41e7224dq6aaedb35cad8d9f2@mail.gmail.com> <6214AB9C-9F9B-4B9D-8B05-0B3DF5F6C16D@SARENET.ES> <20071106100015.GB5268@garage.freebsd.pl> <9A147CEC-D5E6-4117-8C69-16E40DB45B22@SARENET.ES> <20071106125552.GO5268@garage.freebsd.pl>

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My 7.0-BETA2 (+ updates) system is crashing regularly on a kmem_map  
too small panic too.
Yesterday I applied the vm_kern.c.2.patch patch and turned off all of  
my sysctl tweaks.

At first, the system was stable for a day. During that day, I ran   
make -j4 buildworld several times without trouble.

Then started a network transfer. This was a usenet download, on 4 TCP  
channels, for a total of 10Mbps, from a server at a 'ping distance'  
of about 20ms, using hellanzb.py. My guess was that this sort of  
transfer puts some memory pressure on the kernel space.  Running that  
in parallel with the buildworld crashed the system again.

I hope this helps the investigation. Let me know if I can run other  
tests.

- Martijn


=== sudo cat /var/crash/info.2
Dump header from device /dev/da0
   Architecture: i386
   Architecture Version: 2
   Dump Length: 370655232B (353 MB)
   Blocksize: 512
   Dumptime: Tue Nov  6 22:00:28 2007
   Hostname: dupont.plak.net
   Magic: FreeBSD Kernel Dump
   Version String: FreeBSD 7.0-BETA2 #6: Mon Nov  5 14:25:33 UTC 2007
     root@dupont.plak.net:/usr/obj/usr/src/sys/DUPONT
   Panic String: kmem_malloc(90112): kmem_map too small: 295931904  
total allocated
   Dump Parity: 2925288312
   Bounds: 2
   Dump Status: good


Some hardware info:

Intel P4 3GHz hyperthreading processor,
1GB RAM,
intel i915 chipset,
4 SATA disks on i915 (ICH6),
1 compact flash on IDE to boot the system.

Here is some information from the system, after reboot.

=== uname -a
FreeBSD dupont.plak.net 7.0-BETA2 FreeBSD 7.0-BETA2 #6: Mon Nov  5  
14:25:33 UTC 2007     root@dupont.plak.net:/usr/obj/usr/src/sys/ 
DUPONT  i386
=== diff /usr/src/sys/i386/conf/GENERIC /usr/src/sys/i386/conf/DUPONT
21,22d20
< cpu           I486_CPU
< cpu           I586_CPU
24c22
< ident         GENERIC
---
 > ident         DUPONT
=== zfs list
NAME                   USED  AVAIL  REFER  MOUNTPOINT
raid                   552G   325G  1.50K  none
raid/data              547G   325G   471G  /data
raid/data/store1       76.5G   325G  76.5G  /data/store1
raid/data/store2  84.8M   325G  84.8M  /data/store2
raid/sys              4.65G   325G  26.9K  none
raid/sys/home          131M   325G   131M  legacy
raid/sys/root          135M   325G   135M  legacy
raid/sys/tmp          56.9K   325G  56.9K  legacy
raid/sys/usr          2.92G   325G  2.92G  legacy
raid/sys/var          1.47G   325G  1.47G  legacy
raid/sys2              300M   325G  26.9K  none
raid/sys2/root         178M   325G   178M  legacy
raid/sys2/tmp         35.2K   325G  35.2K  legacy
raid/sys2/usr          121M   325G   121M  legacy
raid/sys2/var          291K   325G   291K  legacy
=== zpool status
   pool: raid
state: ONLINE
scrub: none requested
config:

         NAME        STATE     READ WRITE CKSUM
         raid        ONLINE       0     0     0
           raidz1    ONLINE       0     0     0
             ad4     ONLINE       0     0     0
             ad5     ONLINE       0     0     0
             ad6     ONLINE       0     0     0
             ad7     ONLINE       0     0     0

errors: No known data errors
=== cat /boot/loader.conf
# Load ZFS and load root system from the RAID-Z array.
zfs_load="YES"
vfs.root.mountfrom="zfs:raid/sys/root"

# Tune ZFS and VM parameters.
#vfs.zfs.arc_max="64M"
#kern.maxvnodes="50000"
#vm.kmem_size_max="512M"
#vm.kmem_size="512M"
=== sysctl vm | grep kmem
vm.kmem_size_scale: 3
vm.kmem_size_max: 335544320
vm.kmem_size_min: 0
vm.kmem_size: 335544320
=== sysctl vfs.zfs
vfs.zfs.arc_min: 16777216
vfs.zfs.arc_max: 251658240
vfs.zfs.mdcomp_disable: 0
vfs.zfs.prefetch_disable: 0
vfs.zfs.zio.taskq_threads: 0
vfs.zfs.recover: 0
vfs.zfs.vdev.cache.size: 10485760
vfs.zfs.vdev.cache.max: 16384
vfs.zfs.cache_flush_disable: 0
vfs.zfs.zil_disable: 0
vfs.zfs.debug: 0
=== sysctl kstat.zfs
kstat.zfs.misc.arcstats.hits: 602394
kstat.zfs.misc.arcstats.misses: 29556
kstat.zfs.misc.arcstats.demand_data_hits: 475248
kstat.zfs.misc.arcstats.demand_data_misses: 7156
kstat.zfs.misc.arcstats.demand_metadata_hits: 105827
kstat.zfs.misc.arcstats.demand_metadata_misses: 10413
kstat.zfs.misc.arcstats.prefetch_data_hits: 140
kstat.zfs.misc.arcstats.prefetch_data_misses: 4620
kstat.zfs.misc.arcstats.prefetch_metadata_hits: 21179
kstat.zfs.misc.arcstats.prefetch_metadata_misses: 7367
kstat.zfs.misc.arcstats.mru_hits: 242176
kstat.zfs.misc.arcstats.mru_ghost_hits: 3548
kstat.zfs.misc.arcstats.mfu_hits: 338953
kstat.zfs.misc.arcstats.mfu_ghost_hits: 2849
kstat.zfs.misc.arcstats.deleted: 40513
kstat.zfs.misc.arcstats.recycle_miss: 61805
kstat.zfs.misc.arcstats.mutex_miss: 66
kstat.zfs.misc.arcstats.evict_skip: 49115
kstat.zfs.misc.arcstats.hash_elements: 3528
kstat.zfs.misc.arcstats.hash_elements_max: 7423
kstat.zfs.misc.arcstats.hash_collisions: 15472
kstat.zfs.misc.arcstats.hash_chains: 290
kstat.zfs.misc.arcstats.hash_chain_max: 4
kstat.zfs.misc.arcstats.p: 124527736
kstat.zfs.misc.arcstats.c: 126306424
kstat.zfs.misc.arcstats.c_min: 16777216
kstat.zfs.misc.arcstats.c_max: 251658240
kstat.zfs.misc.arcstats.size: 126307328
=== sysctl -a | grep vnode
kern.maxvnodes: 52280
kern.minvnodes: 17426
vm.stats.vm.v_vnodepgsout: 60
vm.stats.vm.v_vnodepgsin: 3719
vm.stats.vm.v_vnodeout: 43
vm.stats.vm.v_vnodein: 3719
vfs.freevnodes: 17385
vfs.wantfreevnodes: 17426
vfs.numvnodes: 18986
debug.sizeof.vnode: 272






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