Re: fio main thread got stuck over the weekend

[Jens Axboe <axboe@xxxxxxxxx>]

On 2014-08-22 14:09, scameron@xxxxxxxxxxxxxxxxxx wrote:
> On Fri, Aug 22, 2014 at 02:04:34PM -0500, Jens Axboe wrote:
> > On 2014-08-11 11:04, scameron@xxxxxxxxxxxxxxxxxx wrote:
> > > On Mon, Aug 11, 2014 at 10:44:23AM -0500, scameron@xxxxxxxxxxxxxxxxxx
> > > wrote:
> > > > Hi,
> > > >
> > > > I was running an fio job over the weekend and the main thread
> > > > seems to have hung.  This in on RHEL6u5 with kernel
> > > > 2.6.32-431.20.3.el6.x86_64 but with a highly modified hpsa
> > > > driver, just in case it matters.
> > > >
> > > > [root@msablackburn saperf]# uname -a
> > > > Linux msablackburn.americas.hpqcorp.net 2.6.32-431.20.3.el6.x86_64 #1 SMP
> > > > Fri Jun 6 18:30:54 EDT 2014 x86_64 x86_64 x86_64 GNU/Linux
> > > > [root@msablackburn saperf]# /usr/local/bin/fio --version
> > > > fio-2.1.11-3-g789d
> > > >
> > > > The jobfile looks like this (note the runtime=216000, that's 60 hours)
> > > > It seems to have hung with about 25 hours remaining.)
> > > >
> > > > [root@msablackburn saperf]# cat 2drive_sdr.fio
> > > > [global]
> > > > direct=1
> > > > ioengine=libaio
> > > > norandommap
> > > > randrepeat=0
> > > > bs=4096
> > > > iodepth=1011
> > > > #iodepth=96
> > > > #numjobs=1
> > > > numjobs=12
> > > > #numjobs=24
> > > > # number_ios=1
> > > > runtime=216000
> > > > #runtime=54000
> > > > time_based=1
> > > > group_reporting
> > > > thread
> > > > gtod_reduce=1
> > > > #iodepth_batch=4
> > > > #iodepth_batch_complete=4
> > > > cpus_allowed=0-5
> > > > cpus_allowed_policy=split
> > > > rw=randread
> > > >
> > > > [4_KiB_RR_drive_r]
> > > > filename=/dev/sdr
> > > >
> > > > [4_KiB_RR_drive_s]
> > > > filename=/dev/sds
> > > >
> > > >
> > > > Here is all the output so far:
> > > >
> > > > ---------------8<------------8<-------------8<-----------------
> > > > [root@msablackburn saperf]# fio 2drive_sdr.fio
> > > > 4_KiB_RR_drive_r: (g=0): rw=randread, bs=4K-4K/4K-4K/4K-4K,
> > > > ioengine=libaio, iodepth=1011
> > > > ...
> > > > 4_KiB_RR_drive_s: (g=0): rw=randread, bs=4K-4K/4K-4K/4K-4K,
> > > > ioengine=libaio, iodepth=1011
> > > > ...
> > > > fio-2.1.11-3-g789d
> > > > Starting 24 threads
> > > > ^Cbs: 24 (f=24): [r(24)] [1.2% done] [1113MB/0KB/0KB /s] [285K/0/0 iops]
> > > > [eta 14h:48m:47s]
> > > > fio: terminating on signal 2
> > > >
> > > > 4_KiB_RR_drive_r: (groupid=0, jobs=24): err= 0: pid=7696: Fri Aug  8
> > > > 16:49:19 2014
> > > >    read : io=881568MB, bw=1309.1MB/s, iops=335341, runt=672989msec
> > > >    cpu          : usr=1.75%, sys=23.15%, ctx=1266117, majf=9, minf=835
> > > >    IO depths    : 1=0.1%, 2=0.1%, 4=0.1%, 8=0.1%, 16=0.1%, 32=0.1%,
> > > >    >=64=100.0%
> > > >       submit    : 0=0.0%, 4=100.0%, 8=0.0%, 16=0.0%, 32=0.0%, 64=0.0%,
> > > >       >=64=0.0%
> > > >       complete  : 0=0.0%, 4=100.0%, 8=0.0%, 16=0.0%, 32=0.0%, 64=0.0%,
> > > >       >=64=0.1%
> > > >       issued    : total=r=225681428/w=0/d=0, short=r=0/w=0/d=0
> > > >       latency   : target=0, window=0, percentile=100.00%, depth=1011
> > > >
> > > > Run status group 0 (all jobs):
> > > >     READ: io=881568MB, aggrb=1309.1MB/s, minb=1309.1MB/s,
> > > >     maxb=1309.1MB/s, mint=672989msec, maxt=672989msec
> > > >
> > > > Disk stats (read/write):
> > > >    sdr: ios=112299535/0, merge=0/0, ticks=13349007/0, in_queue=13054755,
> > > >    util=98.57%
> > > >    sds: ios=113359581/0, merge=0/0, ticks=13710834/0, in_queue=13414931,
> > > >    util=98.71%
> > > > [root@msablackburn saperf]# vi !$
> > > > vi 2drive_sdr.fio
> > > > [root@msablackburn saperf]# fio 2drive_sdr.fio
> > > > 4_KiB_RR_drive_r: (g=0): rw=randread, bs=4K-4K/4K-4K/4K-4K,
> > > > ioengine=libaio, iodepth=1011
> > > > ...
> > > > 4_KiB_RR_drive_s: (g=0): rw=randread, bs=4K-4K/4K-4K/4K-4K,
> > > > ioengine=libaio, iodepth=1011
> > > > ...
> > > > fio-2.1.11-3-g789d
> > > > Starting 24 threads
> > > > Jobs: 24 (f=24): [r(24)] [57.1% done] [1408MB/0KB/0KB /s] [361K/0/0 iops]
> > > > [eta 01d:01h:43m:07s]
> > > > ---------------8<------------8<-------------8<-----------------
> > > >
> > > > And there it sits, the eta does not update.
> > > >
> > > >
> > > > I tried connecting to the process with gdb, and doing "info threads" and
> > > > "bt":
> > > >
> > > > PID of main thread is 8530:
> > > >
> > > > root      8530  598  1.0 2159116 170812 pts/0  Sl+  Aug08 23570:56 fio
> > > > 2drive_sdr.fio
> > > >
> > > > ...
> > > > (gdb) info threads
> > > >    26 Thread 0x7f65da431700 (LWP 8531)  0x0000003aa4cacced in nanosleep
> > > >    () from /lib64/libc.so.6
> > > >    25 Thread 0x7f65d9a30700 (LWP 8532)  0x0000003c69800667 in io_submit
> > > >    () from /lib64/libaio.so.1
> > > >    24 Thread 0x7f65d902f700 (LWP 8533)  0x0000003c69800667 in io_submit
> > > >    () from /lib64/libaio.so.1
> > > >    23 Thread 0x7f65d862e700 (LWP 8534)  0x0000003c69800667 in io_submit
> > > >    () from /lib64/libaio.so.1
> > > >    22 Thread 0x7f65d7c2d700 (LWP 8535)  0x0000003c69800667 in io_submit
> > > >    () from /lib64/libaio.so.1
> > > >    21 Thread 0x7f65d722c700 (LWP 8536)  0x0000003c69800667 in io_submit
> > > >    () from /lib64/libaio.so.1
> > > >    20 Thread 0x7f65d682b700 (LWP 8537)  0x0000003c69800667 in io_submit
> > > >    () from /lib64/libaio.so.1
> > > >    19 Thread 0x7f65d5e2a700 (LWP 8538)  0x0000003c69800667 in io_submit
> > > >    () from /lib64/libaio.so.1
> > > >    18 Thread 0x7f65d5429700 (LWP 8539)  0x0000003c69800667 in io_submit
> > > >    () from /lib64/libaio.so.1
> > > >    17 Thread 0x7f65d4a28700 (LWP 8540)  0x0000003c69800667 in io_submit
> > > >    () from /lib64/libaio.so.1
> > > >    16 Thread 0x7f65d4027700 (LWP 8541)  0x0000003c69800667 in io_submit
> > > >    () from /lib64/libaio.so.1
> > > >    15 Thread 0x7f65d3626700 (LWP 8542)  0x0000003c69800667 in io_submit
> > > >    () from /lib64/libaio.so.1
> > > >    14 Thread 0x7f65d2c25700 (LWP 8543)  0x0000003c69800667 in io_submit
> > > >    () from /lib64/libaio.so.1
> > > >    13 Thread 0x7f65d2222700 (LWP 8544)  0x0000003c69800667 in io_submit
> > > >    () from /lib64/libaio.so.1
> > > >    12 Thread 0x7f65d1820700 (LWP 8545)  0x0000003c69800667 in io_submit
> > > >    () from /lib64/libaio.so.1
> > > >    11 Thread 0x7f65d0e1e700 (LWP 8546)  td_io_queue (td=0x7f65da496410,
> > > >    io_u=0x7f656804d010) at ioengines.c:344
> > > >    10 Thread 0x7f65d041c700 (LWP 8547)  0x0000003c69800667 in io_submit
> > > >    () from /lib64/libaio.so.1
> > > >    9 Thread 0x7f65cfa1a700 (LWP 8548)  0x0000003c69800667 in io_submit ()
> > > >    from /lib64/libaio.so.1
> > > >    8 Thread 0x7f65cf018700 (LWP 8549)  0x0000003c69800667 in io_submit ()
> > > >    from /lib64/libaio.so.1
> > > >    7 Thread 0x7f65ce616700 (LWP 8550)  0x0000003c69800667 in io_submit ()
> > > >    from /lib64/libaio.so.1
> > > >    6 Thread 0x7f65cdc14700 (LWP 8551)  fio_libaio_event
> > > >    (td=0x7f65da4b06a8, event=<value optimized out>) at engines/libaio.c:65
> > > >    5 Thread 0x7f65cd212700 (LWP 8552)  __get_next_offset
> > > >    (td=0x7f65da4b5a60) at io_u.c:389
> > > >    4 Thread 0x7f65cc810700 (LWP 8553)  0x0000003c69800667 in io_submit ()
> > > >    from /lib64/libaio.so.1
> > > >    3 Thread 0x7f65cbe0e700 (LWP 8554)  td_io_u_unlock (td=0x7f65da4c01d0,
> > > >    min_evts=<value optimized out>, bytes=0x7f65cbe0dd10) at fio.h:619
> > > >    2 Thread 0x7f65cb40c700 (LWP 8555)  0x0000003c69800667 in io_submit ()
> > > >    from /lib64/libaio.so.1
> > > > * 1 Thread 0x7f65e34c6720 (LWP 8530)  0x0000003aa4cacced in nanosleep ()
> > > >from /lib64/libc.so.6
> > > > (gdb) bt
> > > > #0  0x0000003aa4cacced in nanosleep () from /lib64/libc.so.6
> > > > #1  0x0000003aa4ce1e44 in usleep () from /lib64/libc.so.6
> > > > #2  0x000000000044afe4 in do_usleep () at backend.c:1727
> > > > #3  run_threads () at backend.c:1965
> > > > #4  0x000000000044b84d in fio_backend () at backend.c:2068
> > > > #5  0x0000003aa4c1ed1d in __libc_start_main () from /lib64/libc.so.6
> > > > #6  0x0000000000409c39 in _start ()
> > > > (gdb) detach
> > > > Detaching from program: /usr/local/bin/fio, process 8530
> > > > (gdb) quit
> > > > [root@msablackburn saperf]#
> > > >
> > > > I am guessing the 8530 thread is the one that prints out the eta updates?
> > > > Well, maybe not, I see a call to create_disk_util_thread() in backend.c.
> > > >
> > > > i/o still seems to be running, and there are no messages in dmesg about
> > > > hung i/o or the scsi mid layer getting angry and trying to abort things
> > > > or anything like that.  Seems to be happily cruising along, except that
> > > > the eta isn't updating, and the job should have finished several hours
> > > > ago now.  I'm leaving it running for now just to try to figure out
> > > > what happened.
> > > >
> > > > Any ideas?  Anything else I should poke at?
> > >
> > > A bit more info:
> > >
> > > thread 26 looks to be the one that's supposed to print the eta info:
> > >
> > > (gdb) thread 26
> > > [Switching to thread 26 (Thread 0x7f65da431700 (LWP 8531))]#0
> > > 0x0000003aa4cacced in nanosleep () from /lib64/libc.so.6
> > > (gdb) bt
> > > #0  0x0000003aa4cacced in nanosleep () from /lib64/libc.so.6
> > > #1  0x0000003aa4ce1e44 in usleep () from /lib64/libc.so.6
> > > #2  0x00000000004474a0 in disk_thread_main (data=<value optimized out>) at
> > > backend.c:1992
> > > #3  0x0000003aa50079d1 in start_thread () from /lib64/libpthread.so.0
> > > #4  0x0000003aa4ce8b5d in clone () from /lib64/libc.so.6
> > > (gdb)
> > >
> > > static void *disk_thread_main(void *data)
> > > {
> > >          int ret = 0;
> > >
> > >          fio_mutex_up(startup_mutex);
> > >
> > >          while (threads && !ret) {
> > >                  usleep(DISK_UTIL_MSEC * 1000);
> > >                  if (!threads)
> > >                          break;
> > >                  ret = update_io_ticks();
> > >
> > >                  if (!is_backend)
> > >                          print_thread_status();
> > >          }
> > >
> > >          fio_mutex_up(disk_thread_mutex);
> > >          return NULL;
> > > }
> > >
> > > that usleep() is where it's in nanosleep, I guess.
> > >from eta.c:
> > > void print_thread_status(void)
> > > {
> > >          struct jobs_eta *je;
> > >          size_t size;
> > >
> > >          je = get_jobs_eta(0, &size);
> > >          if (je)
> > >                  display_thread_status(je);
> > >
> > >          free(je);
> > > }
> > >
> > > Maybe that je is coming back false?  which is
> > > probably the return value of calc_thread_status() which, well,
> > > at a glance, I'm not sure what calc_thread_status() is doing.
> >
> > I'll take a look at this next week, been away at a conference since last
> > weekend.
>
> Ok.  Meantime, I had to reclaim the machine for testing, so I no longer
> have it just sitting there to debug, and I have not sseen the problem again
> that I know of.

Clearly a hardware issue :-)

--
Jens Axboe

--
To unsubscribe from this list: send the line "unsubscribe fio" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at  http://vger.kernel.org/majordomo-info.html