[Scst-devel] [ofa-general] WinOF_2_0_5/SRP initiator: slow reads and eventually hangs

Wed Sep 2 03:01:26 PDT 2009

Chris Worley, on 09/01/2009 11:24 PM wrote:
> On Tue, Sep 1, 2009 at 1:02 PM, Vladislav Bolkhovitin<vst at vlnb.net> wrote:
>> I'd suggest you to enable lockdep on the target. Google for more details how
>> to do it.
>>
>> Also you should additional enable "mgmt_minor" SCST core trace level and
>> only it. Don't enable "all", its output useful only in very special
>> circumstances.
> 
> Could you be more explicit in how to enable specific trace levels?
> 
> For example, "all" causes the following:
> 
> # cat /proc/scsi_tgt/vdisk/trace_level
> out_of_mem | minor | sg | mem | buff | entryexit | pid | line |
> function | debug | special | scsi | mgmt | mgmt_minor | mgmt_dbg |
> order
> # cat /proc/scsi_tgt/trace_level
> out_of_mem | minor | sg | mem | buff | entryexit | pid | line |
> function | debug | special | scsi | mgmt | mgmt_minor | mgmt_dbg |
> retry | scsi_serializing | recv_bot | send_bot | recv_top | send_top
> 
> I tried echoing just some of those flags to cut down on excess
> verbosity, but would get errors like:
> 
> # echo "minor | sg | mem" >/proc/scsi_tgt/vdisk/trace_level
> bash: echo: write error: Invalid argument
> root at fusion-io:/boot# dmesg | tail -1l
> [330010.019198] scst: ***ERROR***: Unknown action "minor | sg | mem"
> 
>> Usually to investigate a problem like yours, the default
>> flags in the debug build + "mgmt_minor" are sufficient.
> 
> I tried "default" and didn't get any messages on the hang.

See /proc/scsi_tgt/help for help about all SCST proc commands. (The 
latest commits have some cleanups in this area.)

> Thanks,
> 
> Chris
>> Vlad
>>
>> Chris Worley, on 09/01/2009 03:04 AM wrote:
>>> On Wed, Aug 12, 2009 at 12:15 AM, Bart Van
>>> Assche<bart.vanassche at gmail.com> wrote:
>>>> On Tue, Aug 11, 2009 at 11:52 PM, Chris Worley<worleys at gmail.com> wrote:
>>>>> I setup my target exactly as you prescribe... but my initiator is
>>>>> still Windows (version of WInOF at top): performance as relayed by
>>>>> IOMeter starts high and the average slowly decreases.  Watching the
>>>>> instantaneous throughput, there seem to be longer and longer lags of
>>>>> poor performance. between moments of good performance.  I need to run
>>>>> this against a Linux initiator to see if the problems are w/ WinOF.
>>>>>
>>>>> Using OFED 1.4.1 (w/ the stock RHEL kernel) on the target, the
>>>>> performance was steady and getting close to acceptable.  In a 15 hour
>>>>> test that cycles through sequential and random LBA's and R/W mixes
>>>>> from block sizes from 1MB to 512B, it worked well and got decent
>>>>> performance until it hit 1KB sequential reads which hung IOMeter; no
>>>>> messages on the Linux side (all looked okay).  IBSRP on the Windows
>>>>> side just said "a reset to device was issued" every 15 to 30 seconds
>>>>> after the problem started. I reloaded the IB stack on the Linux side,
>>>>> and was able to get it restarted.
>>>>>
>>>>> Still a lot of combinations to test.
>>>> Which trace settings are you using on the target ? Enabling the proper
>>>> trace settings via /proc/scsi_tgt/trace_level might reveal whether you
>>>> are e.g. hitting the QUEUE_FULL condition. See also scst/README.
>>> I've found a good kernel/scst mix to easily repeat this; I can get it
>>> to repeatedly hang w/ 8K block transfers running Ubuntu 9.04 w/ the
>>> 2.6.27-14-server kernel on _both_ target and initiator (i.e. no WinOF
>>> or OFED at all) and SCST rev 1062 on the target using one drive
>>> (performance is >600MB/s, >80K IOPS, on the 8KB block sizes being
>>> used).
>>>
>>> Although the problem doesn't occur in Windows until blocks are <2KB
>>> and the RHEL5.2/OFED configuration does not repeat the issue using a
>>> Linux initiator, it seems like a very similar hang, so I'm hoping it's
>>> the same issue.
>>>
>>> To repeat the issue, I run 8KB block random reads w/ 64 threads,
>>> running AIO calls w/ a depth of 64 (using "fio" on the initiator):
>>>
>>> # fio --rw=randrw --bs=8k --rwmixread=100 --numjobs=64 --iodepth=64
>>> --sync=0 --direct=1 --randrepeat=0 --ioengine=libaio
>>> --filename=/dev/sdn --name=test --loops=10000 --size=16091503001
>>>
>>> The "size" represents 10% of the drive.  It doesn't seem to ever
>>> happen on writes, but I've seen it happen on mixed reads/writes.
>>>
>>> With tracing set to "default", there was still nothing in the target
>>> logs at the time of the hang.
>>>
>>> With tracing set thusly on the target:
>>>
>>> echo "all" >/proc/scsi_tgt/trace_level
>>> echo "all" >/proc/scsi_tgt/vdisk/trace_level
>>>
>>> The last few lines of dmesg look like:
>>>
>>> [255354.313411]    0: 28 00 01 84 54 90 00 00 10 00 00 00 00 00 00 00
>>>  (...T...........
>>> [255354.313420] [0]: scst: scst_cmd_init_done:214:tag=62, lun=0, CDB
>>> len=16, queue_type=1 (cmd ffff880102b4a568)
>>> [255354.313443] [26358]: scst: scst_pre_parse:417:op_name <READ(10)>
>>> (cmd ffff880102b4a3a0), direction=2 (expected 2, set yes),
>>> transfer_len=16 (expected len 8192), flags=1
>>> [255354.313420] [0]: scst_cmd_init_done:216:Recieving CDB:
>>> [255354.313452] [8602]: scst: scst_xmit_response:3004:Xmitting data
>>> for cmd ffff880102b49e48 (sg_cnt 0, sg ffff880132579f60, sg[0].page
>>> ffffe200042b7180)
>>> [255354.313457] [8604]: scst: scst_xmit_response:3004:Xmitting data
>>> for cmd ffff880102b4a010 (sg_cnt 0, sg ffff8802e9806f60, sg[0].page
>>> ffffe2000bc129c0)
>>> [255354.313426]  (h)___0__1__2__3__4__5__6__7__8__9__A__B__C__D__E__F
>>> [255354.313426]    0: 28 00 01 bc 5d 10 00 00 10 00 00 00 00 00 00 00
>>>  (...]...........
>>> [255354.313468] [26358]: scst: scst_pre_parse:417:op_name <READ(10)>
>>> (cmd ffff880102b4a568), direction=2 (expected 2, set yes),
>>> transfer_len=16 (expected len 8192), flags=1
>>> [255354.313484] [8602]: scst: scst_xmit_response:3004:Xmitting data
>>> for cmd ffff880102b4a1d8 (sg_cnt 0, sg ffff8802e98064c0, sg[0].page
>>> ffffe2000bc633c0)
>>> [255354.313551] [8604]: scst: scst_xmit_response:3004:Xmitting data
>>> for cmd ffff880102b4a3a0 (sg_cnt 0, sg ffff88018a877060, sg[0].page
>>> ffffe20004300200)
>>> [255354.313556] [8602]: scst: scst_xmit_response:3004:Xmitting data
>>> for cmd ffff880102b4a568 (sg_cnt 0, sg ffff880142581100, sg[0].page
>>> ffffe20004066d40)
>>>
>>> ... and there's a section like:
>>>
>>> [255354.310177]    0: 28 00 01 25 df 50 00 00 10 00 00 00 00 00 00 00
>>>  (..%.P..........
>>> [255354.310177] [0]: scst: scst_cmd_init_done:214:tag=57, lun=0, CDB
>>> len=16, queue_type=1 (cmd ffff8801642e2730)
>>> [255354.310177] [0]: scst_cmd_init_done:216:Recieving CDB:
>>> [255354.310177]  (h)___0__1__2__3__4__5__6__7__8__9__A__B__C__D__E__F
>>> [255354.310177]    0: 28 00 01 5e 22 c0 00 00 10 00 00 00 00 00 00 00
>>>  (..^"...........
>>> [255354.310966] [26369]: scst: scst_pre_parse:417:op_name <READ(10)>
>>> (cmd ffff880168a9e3a0), direction=2 (expected 2, set yes),
>>> transfer_len=16 (expected len 8192), flags=1
>>> [255354.310973] [26361]: scst: scst_pre_parse:417:op_name <READ(10)>
>>> (cmd ffff880168a9e010), direction=2 (expected 2, set yes),
>>> transfer_len=16 (expected len 8192), flags=1
>>> [255354.310980] [26365]: scst: scst_pre_parse:417:op_name <READ(10)>
>>> (cmd ffff880168a9e1d8), direction=2 (expected 2, set yes),
>>> transfer_len=16 (expected len 8192), flags=1
>>> [255354.310986] [26359]: scst: scst_pre_parse:417:op_name <READ(10)>
>>> (cmd ffff880168a9de48), direction=2 (expected 2, set yes),
>>> transfer_len=16 (expected len 8192), flags=1
>>> ...
>>> [255354.311221] [8604]: scst: scst_xmit_response:3004:Xmitting data
>>> for cmd ffff880168a9e1d8 (sg_cnt 0, sg ffff880173ca8060, sg[0].page
>>> ffffe20004325d00)
>>> [255354.311226] [8602]: scst: scst_xmit_response:3004:Xmitting data
>>> for cmd ffff880168a9ee50 (sg_cnt 0, sg ffff880173ca8c40, sg[0].page
>>> ffffe20005847ec0)
>>> [255354.311233] [8604]: scst: scst_xmit_response:3004:Xmitting data
>>> for cmd ffff880168a9dc80 (sg_cnt 0, sg ffff8802f0143c40, sg[0].page
>>> ffffe2000bc04880)
>>> [255354.311238] [8602]: scst: scst_xmit_response:3004:Xmitting data
>>> for cmd ffff880168a9e568 (sg_cnt 0, sg ffff8802f08361a0, sg[0].page
>>> ffffe2000bbf2400)
>>> [255354.311242] [8604]: scst: scst_xmit_response:3004:Xmitting data
>>> for cmd ffff880168a9d560 (sg_cnt 0, sg ffff88010acd74c0, sg[0].page
>>> ffffe200047e7280)
>>>
>>> ... but, prior to that, messages are unreadably garbled, as in:
>>>
>>> Aug 31 22:37:00 nameme kernel: t]9l ft48 r(09 ,83_5p  s20 sg:303
>>> _00s3]c_=cs  _00ad0000e_003a6_0031_4(ea5 9arg )_2As_05s_8[7:c8[f3 _178
>>> 087gff0 .R nt]9i0tmpd1:ft st06s68 5i9[301602_106)o6 _001e4 0<s0 3>)0
>>> .3E3_28a9102 pft0>e_o[.eo[<_2n05 98_0f8_i xpe1f0 D<98s np8one:21_0
>>> 30f3006=e_ ax R8gs=h62]= 2.pd_ pad555mlf
>>> 1_]f8=.05lf i7gxs_ac3 m_0c0:]5i3087[_ 5e sg,00[dc3e,_ 0[ ( 1<[t]F]
>>> ..eb 4t_ ah1,_1_]10.h45_]2,5__12C5o 37 d_.)b_g4f850s, t1e c80.ite.8pE
>>> ue2.4f[.ft0 5c5_1effft 5530 f len=16, 5v03,em_cs4e 05fc78.5r5. n
>>> ,45ft45ff<if_:4fnd5c<ts54c078f9]_0c0a0efee04f[,1n 0 __5deff588=f82
>>> .t)m9.8)9.8077=s  _C 3 i8 .tlsf5_[0s0 (2u fu 4
>>> 5fco5fnr.n0a05_34f__4fd_4n Bs60fn4pB.tor7=s
>>> _i8s7=0_.tl:c>l3e0.51_654.30350en.m C30 C3 e f.dtm0=2_1e0n]6qe  d.>_
>>> 76 d=f _esr_tp 9_50.tnf50[cs.,
>>> Aug 31 22:37:00 nameme kernel: e .0 5 B , 45 0<s382 3_
>>> Aug 31 22:37:00 nameme kernel:  c2< s0< cm38cf58.[f10 002< c3De
>>> _)088m8 9c5299pected__F
>>> Aug 31 22:37:00 nameme kernel: tran50 pt48)=8]=s59etl5pe4e6d)0c6
>>> ei_2(e_<3cc_ ea51es_0_sras A >cmdtesafe4 3[m 3.rer7:[ 1b00s5
>>> Aug 31 22:37:00 nameme kernel: ] 2a015ffs.35fff  B__ a
>>> 6cmd9spre3se9_2e3806(3_csA_  1 ns38ge0sre0
>>> Aug 31 22:37:00 nameme kernel: <g data  sf9_ _ 6d  0se5245f_26._2
>>> .,76.9<g fe t_]t6:(E...:s5D.s0_<Rte46>0330B005]08s3 __ r40r._5x,<Re08
>>> :2ec_ :06cs1_0ti1d l:253064enfe7]0 abd5 0f>196.t b 7.(008ni]
>>> 0s09.r650t, <24]__ s1=in03 s0p c2>>[4ein.1:ooD..ps210a>[25534_r6,:t
>>> n4.]4(8 e2 .r c 2n1g9360]10>(  00 00 00 00[fd[2
>>> [2g_re53  le_6c_md8t_ftc883tf03c  m_0 :8r8fmd63m3:0] 25 c6>[2n_e:fa2e84_0
>>> Aug 31 22:37:00 nameme kernel: c,
>>> Aug 31 22:37:00 nameme kernel: .=0>5f=1s5=1d6_(de:d
>>> 2l_25:0edg25fm>ff40 l440 e,AFg l)AF0 0o[1088. 1aggB
>>> 0n=d9(16a.5oeX6csf00s0: ._, (=10es_(1 7 5c___oR5st_42p3d 7
>>> C9d=5_:(3__7mD4_ 0m4_ed
>>> 04,5.,[s55.d4c,,25=,c8__q,[(meet9303_mr0ue9m0u_032__fy2se
>>> Aug 31 22:37:00 nameme kernel: >  y>i
>>>
>>> ... so other suggestions on trace settings would be appreciated.
>>>
>>> Thanks,
>>>
>>> Chris
>>>> Bart.