On 11/14/2017 03:11 PM, Matthew Rosato wrote:
> On 11/12/2017 01:34 PM, Wei Xu wrote:
>> On Sat, Nov 11, 2017 at 03:59:54PM -0500, Matthew Rosato wrote:
>>>>> This case should be quite similar with pkgten, if you got improvement with
>>>>> pktgen, usually it was also the same for UDP, could you please try to
>>>>> disable
>>>>> tso, gso, gro, ufo on all host tap devices and guest virtio-net devices?
>>>>> Currently
>>>>> the most significant tests would be like this AFAICT:
>>>>>
>>>>> Host->VM 4.12 4.13
>>>>> TCP:
>>>>> UDP:
>>>>> pktgen:
So, I automated these scenarios for extended overnight runs and started
experiencing OOM conditions overnight on a 40G system. I did a bisect
and it also points to c67df11f. I can see a leak in at least all of the
Host->VM testcases (TCP, UDP, pktgen), but the pktgen scenario shows the
fastest leak.
I enabled slub_debug on base 4.13 and ran my pktgen scenario in short
intervals until a large% of host memory was consumed. Numbers below
after the last pktgen run completed. The summary is that a very large #
of active skbuff_head_cache entries can be seen - The sum of alloc/free
calls match up, but the # of active skbuff_head_cache entries keeps
growing each time the workload is run and never goes back down in
between runs.
free -h:
total used free shared buff/cache available
Mem: 39G 31G 6.6G 472K 1.4G 6.8G
OBJS ACTIVE USE OBJ SIZE SLABS OBJ/SLAB CACHE SIZE NAME
1001952 1000610 99% 0.75K 23856 42 763392K skbuff_head_cache
126192 126153 99% 0.36K 2868 44 45888K ksm_rmap_item
100485 100435 99% 0.41K 1305 77 41760K kernfs_node_cache
63294 39598 62% 0.48K 959 66 30688K dentry
31968 31719 99% 0.88K 888 36 28416K inode_cache
/sys/kernel/slab/skbuff_head_cache/alloc_calls :
259 __alloc_skb+0x68/0x188 age=1/135076/135741 pid=0-11776 cpus=0,2,4,18
1000351 __build_skb+0x42/0xb0 age=8114/63172/117830 pid=0-11863 cpus=0,10
/sys/kernel/slab/skbuff_head_cache/free_calls:
13492 <not-available> age=4295073614 pid=0 cpus=0
978298 tun_do_read.part.10+0x18c/0x6a0 age=8532/63624/110571 pid=11733
cpus=1-19
6 skb_free_datagram+0x32/0x78 age=11648/73253/110173 pid=11325
cpus=4,8,10,12,14
3 __dev_kfree_skb_any+0x5e/0x70 age=108957/115043/118269
pid=0-11605 cpus=5,7,12
1 netlink_broadcast_filtered+0x172/0x470 age=136165 pid=1 cpus=4
2 netlink_dump+0x268/0x2a8 age=73236/86857/100479 pid=11325 cpus=4,12
1 netlink_unicast+0x1ae/0x220 age=12991 pid=9922 cpus=12
1 tcp_recvmsg+0x2e2/0xa60 age=0 pid=11776 cpus=6
3 unix_stream_read_generic+0x810/0x908 age=15443/50904/118273
pid=9915-11581 cpus=8,16,18
2 tap_do_read+0x16a/0x488 [tap] age=42338/74246/106155
pid=11605-11699 cpus=2,9
1 macvlan_process_broadcast+0x17e/0x1e0 [macvlan] age=18835
pid=331 cpus=11
8800 pktgen_thread_worker+0x80a/0x16d8 [pktgen] age=8545/62184/110571
pid=11863 cpus=0
By comparison, when running 4.13 with c67df11f reverted, here's the same
output after the exact same test:
free -h:
total used free shared buff/cache available
Mem: 39G 783M 37G 472K 637M 37G
slabtop:
OBJS ACTIVE USE OBJ SIZE SLABS OBJ/SLAB CACHE SIZE NAME
714 256 35% 0.75K 17 42 544K skbuff_head_cache
/sys/kernel/slab/skbuff_head_cache/alloc_calls:
257 __alloc_skb+0x68/0x188 age=0/65252/65507 pid=1-11768 cpus=10,15
/sys/kernel/slab/skbuff_head_cache/free_calls:
255 <not-available> age=4295003081 pid=0 cpus=0
1 netlink_broadcast_filtered+0x2e8/0x4e0 age=65601 pid=1 cpus=15
1 tcp_recvmsg+0x2e2/0xa60 age=0 pid=11768 cpus=16
