[Borgbackup] Decreasing speed of borg check command?

[Marcin Zajączkowski]

Hi,

I would like to consult one observation. Performing a 600GB+ repo check,
the HDD read speed started at ~110MB/s (USB3 HDD drive), but over time
tends to decease up until ~60MB/s after 2 hours. Disk transfer data from
dstat.

> ----system---- --dsk/sdc-- -net/total- ---system-- ----total-usage----
>      time     | read  writ| recv  send| int   csw |usr sys idl wai stl
...
> 02-04 23:28:20| 111M    0 | 213   269 |2620  5023 |  6   7  84   3   0
> 02-04 23:28:25| 110M    0 | 171   199 |4277  8007 | 13   8  72   7   0
> 02-04 23:28:30| 110M    0 | 342   199 |3926  8305 | 12   7  73   6   0
...
> 03-04 00:03:50|  95M    0 |   0     0 |2827  5536 |  7   6  81   5   0
> 03-04 00:03:55|  93M    0 |   0     0 |4306    14k|  9   7  80   4   0
> 03-04 00:04:00|  95M    0 |   0     0 |3366  6121 |  8   7  79   6   0
...
> 03-04 01:18:20|  57M    0 |   0     0 |1294  2557 |  3   4  91   2   0
> 03-04 01:18:25|  57M    0 |   0     0 |1184  2433 |  2   4  90   3   0
> 03-04 01:18:30|  57M    0 | 592   592 |1301  2339 |  3   4  92   1   0


It may caused by some other reasons (but rather not a fragmentation - it
was after an initial test backup performed to an empty disk), but it
could be also some kind of memory leak in Borg which leads to keeping
more and more data internally over time causing that slowness.

Do you have an idea what could it be caused by?

I may try reproduce that behavior later on this month if needed. Borg
1.1.8, Fedora 29.

Marcin

-- 
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