zfs, a directory that used to hold lot of files and listing pause

[Steven Hartland]

On 21/10/2016 10:04, Eugene M. Zheganin wrote:
> Hi.
>
> On 21.10.2016 9:22, Steven Hartland wrote:
>> On 21/10/2016 04:52, Eugene M. Zheganin wrote:
>>> Hi.
>>>
>>> On 20.10.2016 21:17, Steven Hartland wrote:
>>>> Do you have atime enabled for the relevant volume?
>>> I do.
>>>>
>>>> If so disable it and see if that helps:
>>>> zfs set atime=off <volume>
>>>>
>>> Nah, it doesn't help at all.
>> As per with Jonathon what does gstat -pd and top -SHz show? 
>
> gstat (while ls'ing):
>
> dT: 1.005s  w: 1.000s
>  L(q)  ops/s    r/s   kBps   ms/r    w/s   kBps   ms/w    d/s kBps   
> ms/d   %busy Name
>     1     49     49   2948   13.5      0      0    0.0      0 0 0.0   
> 65.0| ada0
>     0     32     32   1798   11.1      0      0    0.0      0 0 0.0   
> 35.3| ada1
>
Averagely busy then on rust.
> gstat (while idling):
>
> dT: 1.003s  w: 1.000s
>  L(q)  ops/s    r/s   kBps   ms/r    w/s   kBps   ms/w    d/s kBps   
> ms/d   %busy Name
>     0      0      0      0    0.0      0      0    0.0      0 0 0.0    
> 0.0| ada0
>     0      2      2    255    0.8      0      0    0.0      0 0 0.0    
> 0.1| ada1
>
> top -SHz output doesn't really differ while ls'ing or idling:
>
> last pid: 12351;  load averages:  0.46,  0.49, 
> 0.46                                           up 39+14:41:02 14:03:05
> 376 processes: 3 running, 354 sleeping, 19 waiting
> CPU:  5.8% user,  0.0% nice, 16.3% system,  0.0% interrupt, 77.9% idle
> Mem: 21M Active, 646M Inact, 931M Wired, 2311M Free
> ARC: 73M Total, 3396K MFU, 21M MRU, 545K Anon, 1292K Header, 47M Other
> Swap: 4096M Total, 4096M Free
>
>   PID USERNAME   PRI NICE   SIZE    RES STATE   C   TIME    WCPU COMMAND
>   600 root        39    0 27564K  5072K nanslp  1 295.0H  24.56% monit
>     0 root       -17    0     0K  2608K -       1  75:24   0.00% 
> kernel{zio_write_issue}
>   767 freeswitch  20    0   139M 31668K uwait   0  48:29   0.00% 
> freeswitch{freeswitch}
>   683 asterisk    20    0   806M   483M uwait   0  41:09   0.00% 
> asterisk{asterisk}
>     0 root        -8    0     0K  2608K -       0  37:43   0.00% 
> kernel{metaslab_group_t}
> [... others lines are just 0% ...]
This looks like you only have ~4Gb ram which is pretty low for ZFS I 
suspect vfs.zfs.prefetch_disable will be 1, which will crash the 
performance.

     Regards
     Steve