[CRIU] Memory dump time with incremental checkpoint

[Ranjan Sarpangala Venkatesh]

Hello,

Any insights on why incrementally(local checkpoints) dumping a fewer number
of pages are taking longer time. The checkpoint images are all stored on
ramfs(DRAM, no swap as well) based directories. The details are below.
Thanks

Regards
Ranjan

On Wed, May 23, 2018 at 10:58 PM Ranjan Sarpangala Venkatesh <
ranjansv at gmail.com> wrote:

> Hi,
>
> Following are the statistics collected while creating incremental dumps of
> an application using
>
> criu dump --tree $PID --images-dir ./checkpoints/$i/ --leave-running -vvv
> -o dump.log
>
> Dump 1, "pages_written": 2832, "memwrite_time": 11743,
> Dump 2,  "pages_written": 2034, "memwrite_time": 45700,
>
> Dump 2 takes much longer while writing less number of pages. Is this due
> to behavior of splice(). Custom kernel version based on 4.10.0. Any
> insights would be helpful. Thanks
>
> $crit show 1/stats-dump
> {
>     "magic": "STATS",
>     "entries": [
>         {
>             "dump": {
>                 "freezing_time": 273,
>                 "frozen_time": 24271,
>                 "memdump_time": 14884,
>                 "memwrite_time": 11743,
>                 "pages_scanned": 9566,
>                 "pages_skipped_parent": 0,
>                 "pages_written": 2832,
>                 "irmap_resolve": 0
>             }
>         }
>     ]
> }
>
> $crit show 2/stats-dump
> {
>     "magic": "STATS",
>     "entries": [
>         {
>             "dump": {
>                 "freezing_time": 122,
>                 "frozen_time": 55545,
>                 "memdump_time": 49705,
>                 "memwrite_time": 45700,
>                 "pages_scanned": 5873,
>                 "pages_skipped_parent": 0,
>                 "pages_written": 2034,
>                 "irmap_resolve": 0
>             }
>         }
>     ]
> }
>
> Regards
> Ranjan
>
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