[stgt] tgtd memory usage

Stepan Fedorov stepan.fedorov at clodo.ru
Thu Mar 24 22:10:39 CET 2011

OK! I do some tests on my test environment and here is the results:

My target node has 12Gb of memory. I created 300 LUN's on it - tgtd process virtual size become something above 13Gb.

Next, i attach this LUNs on three initiator nodes - 100 LUNs per node.

Now - my task is to initiate some IO on all of this LUNs in parallel, to see - what happen with tgtd.

To do this, i created LVM striped volume (/dev/vbd0/megadisk0) from 100 iSER-attached LUNs on each initiator node.

Next, i run e2fsck /dev/vbd0/megadisk0 on three nodes. During this process, i got messages about IO errors on all LUNs in dmesg on all three nodes, because tgtd segfaults on target node, with this message in dmesg:
 [734121.705847] tgtd[18959]: segfault at 0 ip (null) sp 00007fff04d22118 error 14 in tgtd[400000+4a000]

24.03.2011, в 14:06, FUJITA Tomonori написал(а):

> On Thu, 24 Mar 2011 14:09:14 +0300
> Степан Фёдоров <stepan.fedorov at clodo.ru> wrote:
>> Hm... i create 666 targets with one LUN per target on node with 12Gb
>> of memory, and in top i see this:
>>                                                                 7862
>> root       20   0 22.4g  1.6g 1144 S    2 13.4   7:39.18
>> /usr/sbin/tgtd
>> VIRT, and RES values grows while i attach this targets on initiator
>> node. What will happen, if tgt begin usage of all this memory while
>> serving it's targets? It will be killed by oom killer?
> tgtd can avoid oom killer by setting /proc/{pid}/oom_adj.
>> Ooops. While i write this - on initiator side i got in dmesg a "BUG" message )
> Needs to report it to open-iscsi mailing list.

Stepan Fedorov
sf at clodo.ru

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