Re: ZFS kmem_map too small.

On Mon, 8 Oct 2007, Pawel Jakub Dawidek wrote:
> Here are some updates:
>
> I was able to reproduce the panic by rsyncing big files and trying
> bonnie++ test suggested in this thread.
>
> Can you guys retry with this patch:
>
> 	http://people.freebsd.org/~pjd/patches/vm_kern.c.2.patch
>
> It's a hack, yes, but allows to mitigate the problem quite well. I'm
> looking for a solution that can be used for 7.0 before we find a better
> fix.
>
> BTW. To use ZFS you _must_ increase vm.kmem_size/vm.kmem_size_max.
> If you have the problem discussed here and you're using standard values,
> please retry with vm.kmem_size/vm.kmem_size_max set to at least 600MB in
> /boot/loader.conf.
>
> I'm not sure if it's not too late to ask re_at_ about increasing the
> default kmem size at least on amd64. ~300MB we have there is silly
> small.

   The latest patch does keep the system surviving longer than before;
however, it eventually panicked with different message.

- Testing case:

 	while true; do
 		bonnie++ -s 2048 -c 50 -x 20
 	done

- ZFS related settings:

 	vfs.root.mountfrom="zfs:universe"
 	vm.kmem_size_max="629145600"
 	vm.kmem_size="629145600"

- zpool status:
   pool: universe
  state: ONLINE
  scrub: none requested
config:

         NAME        STATE     READ WRITE CKSUM
         universe    ONLINE       0     0     0
           ad0s3d    ONLINE       0     0     0

errors: No known data errors

- panic messages:
Fatal trap 12: page fault while in kernel mode
cpuid = 0; apic id = 00
fault virtual address   = 0x3916545d
fault code              = supervisor write, page not present
instruction pointer     = 0x20:0xc04d33c0
stack pointer           = 0x28:0xf7b0e930
frame pointer           = 0x28:0xf7b0e944
code segment            = base 0x0, limit 0xfffff, type 0x1b
                         = DPL 0, pres 1, def32 1, gran 1
processor eflags        = interrupt enabled, resume, IOPL = 0
current process         = 3477 (bonnie++)
[thread pid 3477 tid 100159 ]
Stopped at	malloc_type_zone_allocated+0x70:	addb %cl,0x758bf45d(%ebx)
db> wh
Tracing pid 3477 tid 100159 td 0xc4258a50
malloc_type_zone_allocated(c1076d20,0,2,1,0,...) at
malloc_type_zone_allocated+0x70
malloc(40,c0824060,2,f7b0e9fc,c080df70,...) at malloc+0x69
zfs_kmem_alloc(40,2,c0607d3e,c3d66228,f7b0e998,...) at zfs_kmem_alloc+0x20
zfs_range_lock(c90da0ec,22f2da,0,1,0,...) at zfs_range_lock+0x20
zfs_freebsd_write(f7b0ebc4,0,0,0,c06be120,...) at zfs_freebsd_write+0x24b
VOP_WRITE_APV(c08257c0,f7b0ebc4,c4258a50,c068d7f8,242,...) at VOP_WRITE_APV+0xb6
vn_write(c53bd0d8,f7b0ec60,c7835e00,0,c4258a50,...) at vn_write+0x247
dofilewrite(f7b0ec60,ffffffff,ffffffff,0,c53bd0d8,...) at dofilewrite+0x97
kern_writev(c4258a50,3,f7b0ec60,bfbfdf8b,1,...) at kern_writev+0x58
write(c4258a50,f7b0ecfc,c,f7b0eca4,c065d061,...) at write+0x4f
syscall(f7b0ed38) at syscall+0x319
Xint0x80_syscall() at Xint0x80_syscall+0x20
--- syscall (4, FreeBSD ELF32, write), eip = 0x282779a3, esp = 0xbfbfdf3c, ebp = 0xbfbfdf58 ---
db>

-- 
Cheers,

Tai-hwa Liang