Take the 2-minute tour ×
Server Fault is a question and answer site for system and network administrators. It's 100% free, no registration required.

We have a CentOS 6.3 iscsi server (16GB RAM) running on Infiniband bus (ipoib).

When the load is high I can see multiple errors:

Sep  3 23:22:20 stor4 kernel: tgtd: page allocation failure. order:2, mode:0x20
Sep  3 23:22:20 stor4 kernel: Pid: 3637, comm: tgtd Not tainted 2.6.32 #1
Sep  3 23:22:20 stor4 kernel: Call Trace:
Sep  3 23:22:20 stor4 kernel: [] ? __alloc_pages_nodemask+0x77f/0x940
Sep  3 23:22:20 stor4 kernel: [] ? kmem_getpages+0x62/0x170
Sep  3 23:22:20 stor4 kernel: [] ? fallback_alloc+0x1ba/0x270
Sep  3 23:22:20 stor4 kernel: [] ? cache_grow+0x2cf/0x320
Sep  3 23:22:20 stor4 kernel: [] ? ____cache_alloc_node+0x99/0x160
Sep  3 23:22:20 stor4 kernel: [] ? pskb_expand_head+0x64/0x270
Sep  3 23:22:20 stor4 kernel: [] ? __kmalloc+0x189/0x220
Sep  3 23:22:20 stor4 kernel: [] ? pskb_expand_head+0x64/0x270
Sep  3 23:22:20 stor4 kernel: [] ? __pskb_pull_tail+0x2aa/0x360
Sep  3 23:22:20 stor4 kernel: [] ? tcp_init_tso_segs+0x37/0x50
Sep  3 23:22:20 stor4 kernel: [] ? dev_queue_xmit+0x4bb/0x6f0
Sep  3 23:22:20 stor4 kernel: [] ? neigh_connected_output+0xbd/0x100
Sep  3 23:22:20 stor4 kernel: [] ? ip_finish_output+0x237/0x310
Sep  3 23:22:20 stor4 kernel: [] ? ip_output+0xb8/0xc0
Sep  3 23:22:20 stor4 kernel: [] ? __ip_local_out+0x9f/0xb0
Sep  3 23:22:20 stor4 kernel: [] ? ip_local_out+0x25/0x30
Sep  3 23:22:20 stor4 kernel: [] ? ip_queue_xmit+0x190/0x420
Sep  3 23:22:20 stor4 kernel: [] ? sock_aio_write+0x167/0x180
Sep  3 23:22:20 stor4 kernel: [] ? tcp_transmit_skb+0x3fe/0x7b0
Sep  3 23:22:20 stor4 kernel: [] ? tcp_write_xmit+0x1fb/0xa20
Sep  3 23:22:20 stor4 kernel: [] ? __tcp_push_pending_frames+0x30/0xe0
Sep  3 23:22:20 stor4 kernel: [] ? tcp_push_pending_frames+0x33/0x40
Sep  3 23:22:20 stor4 kernel: [] ? do_tcp_setsockopt+0x3d6/0x480
Sep  3 23:22:20 stor4 kernel: [] ? tcp_setsockopt+0x2a/0x30
Sep  3 23:22:20 stor4 kernel: [] ? sock_common_setsockopt+0x14/0x20
Sep  3 23:22:20 stor4 kernel: [] ? sys_setsockopt+0x7f/0xe0
Sep  3 23:22:20 stor4 kernel: [] ? system_call_fastpath+0x16/0x1b
Sep  3 23:22:20 stor4 kernel: Mem-Info:
Sep  3 23:22:20 stor4 kernel: Node 0 DMA per-cpu:
Sep  3 23:22:20 stor4 kernel: CPU    0: hi:    0, btch:   1 usd:   0
Sep  3 23:22:20 stor4 kernel: CPU    1: hi:    0, btch:   1 usd:   0
Sep  3 23:22:20 stor4 kernel: CPU    2: hi:    0, btch:   1 usd:   0
Sep  3 23:22:20 stor4 kernel: CPU    3: hi:    0, btch:   1 usd:   0
Sep  3 23:22:20 stor4 kernel: Node 0 DMA32 per-cpu:
Sep  3 23:22:20 stor4 kernel: CPU    0: hi:  186, btch:  31 usd: 183
Sep  3 23:22:20 stor4 kernel: CPU    1: hi:  186, btch:  31 usd:  23
Sep  3 23:22:20 stor4 kernel: CPU    2: hi:  186, btch:  31 usd: 183
Sep  3 23:22:20 stor4 kernel: CPU    3: hi:  186, btch:  31 usd: 181
Sep  3 23:22:20 stor4 kernel: Node 0 Normal per-cpu:
Sep  3 23:22:20 stor4 kernel: CPU    0: hi:  186, btch:  31 usd: 171
Sep  3 23:22:20 stor4 kernel: CPU    1: hi:  186, btch:  31 usd:  29
Sep  3 23:22:20 stor4 kernel: CPU    2: hi:  186, btch:  31 usd:  32
Sep  3 23:22:20 stor4 kernel: CPU    3: hi:  186, btch:  31 usd:  32
Sep  3 23:22:20 stor4 kernel: active_anon:1875 inactive_anon:2473 isolated_anon:0
Sep  3 23:22:20 stor4 kernel: active_file:1243637 inactive_file:2505055 isolated_file:0
Sep  3 23:22:20 stor4 kernel: unevictable:0 dirty:268338 writeback:0 unstable:0
Sep  3 23:22:20 stor4 kernel: free:86050 slab_reclaimable:132377 slab_unreclaimable:23744
Sep  3 23:22:20 stor4 kernel: mapped:1293 shmem:222 pagetables:720 bounce:0
Sep  3 23:22:20 stor4 kernel: Node 0 DMA free:15732kB min:124kB low:152kB high:184kB active_anon:0kB inactive_anon:0kB active_file:0kB inactive_file:0kB unevictable:0kB isolated(anon):0kB isolated(file):0kB present:15332kB mlocked:0kB dirty:0kB writeback:0kB mapped:0kB shmem:0kB slab_reclaimable:0kB slab_unreclaimable:0kB kernel_stack:0kB pagetables:0kB unstable:0kB bounce:0kB writeback_tmp:0kB pages_scanned:0 all_unreclaimable? yes
Sep  3 23:22:20 stor4 kernel: lowmem_reserve[]: 0 2172 16060 16060
Sep  3 23:22:20 stor4 kernel: Node 0 DMA32 free:107544kB min:18268kB low:22832kB high:27400kB active_anon:468kB inactive_anon:2364kB active_file:566208kB inactive_file:976112kB unevictable:0kB isolated(anon):0kB isolated(file):0kB present:2224900kB mlocked:0kB dirty:96816kB writeback:0kB mapped:908kB shmem:12kB slab_reclaimable:176940kB slab_unreclaimable:968kB kernel_stack:64kB pagetables:192kB unstable:0kB bounce:0kB writeback_tmp:0kB pages_scanned:0 all_unreclaimable? no
Sep  3 23:22:20 stor4 kernel: lowmem_reserve[]: 0 0 13887 13887
Sep  3 23:22:20 stor4 kernel: Node 0 Normal free:220924kB min:116772kB low:145964kB high:175156kB active_anon:7032kB inactive_anon:7528kB active_file:4408340kB inactive_file:9044108kB unevictable:0kB isolated(anon):0kB isolated(file):0kB present:14220800kB mlocked:0kB dirty:976536kB writeback:0kB mapped:4264kB shmem:876kB slab_reclaimable:352568kB slab_unreclaimable:94008kB kernel_stack:2048kB pagetables:2688kB unstable:0kB bounce:0kB writeback_tmp:0kB pages_scanned:0 all_unreclaimable? no
Sep  3 23:22:20 stor4 kernel: lowmem_reserve[]: 0 0 0 0
Sep  3 23:22:20 stor4 kernel: Node 0 DMA: 1*4kB 0*8kB 1*16kB 1*32kB 1*64kB 0*128kB 1*256kB 0*512kB 1*1024kB 1*2048kB 3*4096kB = 15732kB
Sep  3 23:22:20 stor4 kernel: Node 0 DMA32: 16305*4kB 4381*8kB 353*16kB 8*32kB 1*64kB 1*128kB 0*256kB 1*512kB 1*1024kB 0*2048kB 0*4096kB = 107900kB
Sep  3 23:22:20 stor4 kernel: Node 0 Normal: 14548*4kB 14808*8kB 2420*16kB 31*32kB 5*64kB 0*128kB 0*256kB 0*512kB 0*1024kB 0*2048kB 1*4096kB = 220784kB
Sep  3 23:22:20 stor4 kernel: 3748822 total pagecache pages
Sep  3 23:22:20 stor4 kernel: 0 pages in swap cache
Sep  3 23:22:20 stor4 kernel: Swap cache stats: add 0, delete 0, find 0/0
Sep  3 23:22:20 stor4 kernel: Free swap  = 975864kB
Sep  3 23:22:20 stor4 kernel: Total swap = 975864kB
Sep  3 23:22:20 stor4 kernel: 4194303 pages RAM
Sep  3 23:22:20 stor4 kernel: 126915 pages reserved
Sep  3 23:22:20 stor4 kernel: 3753534 pages shared
Sep  3 23:22:20 stor4 kernel: 213500 pages non-shared

TCP stack and VM config:

net.core.rmem_max = 83886080
net.core.wmem_max = 83886080
net.core.rmem_default = 65536
net.core.wmem_default = 65536
net.ipv4.tcp_rmem = 40960 1048560 4194304
net.ipv4.tcp_wmem = 40960 196608  4194304
net.ipv4.tcp_mem = 16388608 16388608 16388608
vm.min_free_kbytes=135168

Additional tweaks:

/sbin/blockdev --setra 16384 /dev/sdb
echo 2048 > /sys/block/sdb/queue/nr_requests

Where might the problem be? Thank you.

share|improve this question

1 Answer 1

A few things you can try... but iSCSI over IPoIB sounds a little messy. Obviously, performance must matter if you're using Infiniband.

  • Outside of the errors, how is performance?
  • Is this reproducible? Can you trigger it on demand or are the messages just piling up in the dmesg ring buffer?
  • What filesystem are you using on the mounted iSCSI device? That may have an influence on my recommendations.

Anyway, since you're on CentOS 6.3, I'd seriously consider enabling the tuned-adm profile set. For you, if it's not already installed, run yum install tuned tuned-utils and try the "enterprise storage" profile:

tuned-adm profile enterprise-storage

That will move your I/O elevators to deadline scheduler, change the kernel.sched_min_ granularity_ns to 10ms, make a few tweaks to the vm subsystem, remove write barriers, modify the CPU governor and boost the disk read-ahead. You can also move your sysctl and sysfs settings to a custom profile.

Reverting to your original settings can be done with tuned-adm off. These commands are safe to run on the fly. Can you test and report back?

share|improve this answer
1  
Thank you! After googling I found that I'm getting these errors because of bug in rhel 6.2 and above: bugzilla.redhat.com/show_bug.cgi?id=770545. After sysctl -w vm.zone_reclaim_mode=1 errors seem to disappear. –  Dave Sep 3 '12 at 22:04
    
About your questions: 1. The performance is fine. We had SRP instead of IPoIB + iSCSI, but the SCST driver hang on high load causing a SCSI reset. 2. The bug is reproducible: it appeared on every high load (writes). 3. ext3 and ntfs for Windows. –  Dave Sep 3 '12 at 22:11

Your Answer

 
discard

By posting your answer, you agree to the privacy policy and terms of service.

Not the answer you're looking for? Browse other questions tagged or ask your own question.