zfs discuss - Feb 2008 - Did MDB Functionality Change?

On Solaris 10 u3 (11/06) I can execute the following:

bash-3.00# mdb -k
Loading modules: [ unix krtld genunix specfs dtrace ufs sd pcipsy ip sctp usba
nca md zfs random ipc nfs crypto cpc fctl fcip logindmux ptm sppp
]
> arc::print
{
    anon = ARC_anon
    mru = ARC_mru
    mru_ghost = ARC_mru_ghost
    mfu = ARC_mfu
    mfu_ghost = ARC_mfu_ghost
    size = 0x6b800
    p = 0x3f83f80
    c = 0x7f07f00
    c_min = 0x7f07f00
    c_max = 0xbe8be800
    hits = 0x30291
    misses = 0x4f
    deleted = 0xe
    skipped = 0
    hash_elements = 0x3a
    hash_elements_max = 0x3a
    hash_collisions = 0x3
    hash_chains = 0x1
    hash_chain_max = 0x1
    no_grow = 0
}

However, when I execute the same command on Solaris 10 u4 (8/07) I receive the
following error:

bash-3.00# mdb -k
Loading modules: [ unix krtld genunix specfs dtrace ufs ssd fcp fctl qlc pcisch
md ip hook neti sctp arp usba nca lofs logindmux ptm cpc fcip sppp random sd
crypto zfs ipc nfs ]
> arc::print
mdb: failed to dereference symbol: unknown symbol name

In addition, u3 doesn''t recognize "::arc" where u4 does.
u3 displays memory locations with "arc::print -a" where "::arc
-a" doesn''t work for u4.

I posted this into the zfs discussion forum, because this limited u4
functionality prevents you from dynamically changing the ARC in ZFS by trying
the ZFS Tuning instructions.


Spencer
 
 
This message posted from opensolaris.org

Hi Spencer,

spencer wrote:
> On Solaris 10 u3 (11/06) I can execute the following:
>
> bash-3.00# mdb -k
> Loading modules: [ unix krtld genunix specfs dtrace ufs sd pcipsy ip sctp
usba nca md zfs random ipc nfs crypto cpc fctl fcip logindmux ptm sppp ]
>   
>> arc::print
>>     
> {
>     anon = ARC_anon
>     mru = ARC_mru
>     mru_ghost = ARC_mru_ghost
>     mfu = ARC_mfu
>     mfu_ghost = ARC_mfu_ghost
>     size = 0x6b800
>     p = 0x3f83f80
>     c = 0x7f07f00
>     c_min = 0x7f07f00
>     c_max = 0xbe8be800
>     hits = 0x30291
>     misses = 0x4f
>     deleted = 0xe
>     skipped = 0
>     hash_elements = 0x3a
>     hash_elements_max = 0x3a
>     hash_collisions = 0x3
>     hash_chains = 0x1
>     hash_chain_max = 0x1
>     no_grow = 0
> }
>
> However, when I execute the same command on Solaris 10 u4 (8/07) I receive
the following error:
>
> bash-3.00# mdb -k
> Loading modules: [ unix krtld genunix specfs dtrace ufs ssd fcp fctl qlc
pcisch md ip hook neti sctp arp usba nca lofs logindmux ptm cpc fcip sppp random
sd crypto zfs ipc nfs ]
>   
>> arc::print
>>     
> mdb: failed to dereference symbol: unknown symbol name
>   
mdb functionality did not change.  There is no longer a global variable 
named "arc".  The "::arc" command
gets its data from a few different variables.  You can look at 
usr/src/cmd/mdb/common/modules/zfs/zfs.c
and look at the arc_print function to see what it does.  Or, you can use 
::nm !grep arc | grep OBJT
to see what arc related variables exist and use one of those with ::print.
For instance, arc_stats::print.

max
> In addition, u3 doesn''t recognize "::arc" where u4 does.
> u3 displays memory locations with "arc::print -a" where
"::arc -a" doesn''t work for u4.
>
> I posted this into the zfs discussion forum, because this limited u4
functionality prevents you from dynamically changing the ARC in ZFS by trying
the ZFS Tuning instructions.
>
>
> Spencer
>  
>  
> This message posted from opensolaris.org
> _______________________________________________
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> zfs-discuss at opensolaris.org
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>
>