Re: Long rm times of ccreg40 R4 files

[Edward Shishkin <edward.shishkin@gmail.com>]

Dushan Tcholich wrote:
> I was restructuring my partition layout on some disk where I had plain
> R4, and while doing it I deleted some large files.
> I was suprised how short delete times were.
> So on cc partition I created incompressable file ( as per Edwards
> instructions http://marc.info/?l=reiserfs-devel&m=121262617103900&w=2)
> and:
>
> localhost ~ # ls -l /w*
> -rw-r--r-- 1 root root 2600005632 Apr 23 10:22 /windows.qcow2
> localhost ~ # time rm /windows.qcow2
>
> real    0m0.537s
> user    0m0.000s
> sys     0m0.456s
>
> But when that file is managed with ccreg40 plugin on same partition:
> localhost ~ # ls -l /w*
> -r--r--r-- 1 root root 2600005632 Apr 23 10:29 /w.qcow2
> localhost ~ # time rm /w.qcow2
>
> real    1m1.523s
> user    0m0.000s
> sys     0m17.685s
>
>   

Data of a large ccreg40 file is scattered on many-many formatted
nodes, so in order to delete such file we need to scan the tree and
perform expensive surgery.

While a reg40 file is just one extent pointer in a formatted node :)

Edward.

> iotop: 2044 be/4 root       16.23 M/s   16.25 M/s  ?unavailable?  rm /w.qcow2
>
> If I can give any more data feel free to ask
>
> Have a nice day
>
> Dushan
>
> PS.
> localhost ~ # uname -a
> Linux localhost 2.6.31-hh #1 SMP Sat Feb 6 17:58:52 CET 2010 x86_64
> Intel(R) Core(TM)2 CPU 6400 @ 2.13GHz GenuineIntel GNU/Linux
>
> /dev/md2                /               reiser4         noatime         0 0
>
> Partition on Raid1 created with plain mkfs.reiser4 -o create=ccreg40
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