Slowdown during unpacking/multicore par2

[Headcase_Fargone]

I only just recently started using SABNZBD (I'm new to the whole Usenet thing) and it's been working great so far. There's only one minor snag that I've been running into in regards to performance. This is running on a very low-power machine, one of those dual core AMD E350 APUs. The machine acts as media server as well as downloading, light hosting, etc. Everything is fine except when post processing starts. I get some pretty severe slowdown when streaming media from the device once unpacking begins.

I've done some searching around and it seems that I might need to use the "-t+" switch for par2, but I'm unsure of what version of par2 I'm running or if this will even help me. Why would I want it to use both cores if it's already tapping the box's resources at its current settings?

So with that in mind, what's my most likely solution to prevent it killing streaming performance when it unpacks? Something like IOnice? A new version of par2?

Thanks in advance.

[shypike]

The disk is often the bottleneck when unpacking and watching at the same time.
Using -t+ is detrimental for your disk performance.
It's better to use -t0
On a slow system you'd better not watch and unpack at the same time.

[Headcase_Fargone]

How can I tell what version of par2 I'm using? I've read that Ubuntu doesn't come with the multicore version. Disk IO really shouldn't be an issue. I'm running a four disk array in RAID5 and get pretty decent read/write performance.

[sander]

How can I tell what version of par2 I'm using? I've read that Ubuntu doesn't come with the multicore version. Disk IO really shouldn't be an issue. I'm running a four disk array in RAID5 and get pretty decent read/write performance.

Open a terminal, and type "par2" and then <enter>. BTW: my par2 (Ubuntu) has no "-t+" option: see below.

You can see how your CPU cores are used with System Monitor -> Resources. Or install and use "htop", which is a commandline tool to show process and CPU-core usage.

Code: Select all

sander@netbook:~$ par2
Not enough command line arguments.
par2cmdline version 0.4, Copyright (C) 2003 Peter Brian Clements.

par2cmdline comes with ABSOLUTELY NO WARRANTY.

This is free software, and you are welcome to redistribute it and/or modify
it under the terms of the GNU General Public License as published by the
Free Software Foundation; either version 2 of the License, or (at your
option) any later version. See COPYING for details.

Usage:

  par2 c(reate) [options] <par2 file> [files] : Create PAR2 files
  par2 v(erify) [options] <par2 file> [files] : Verify files using PAR2 file
  par2 r(epair) [options] <par2 file> [files] : Repair files using PAR2 files

You may also leave out the "c", "v", and "r" commands by using "parcreate",
"par2verify", or "par2repair" instead.

Options:

  -b<n>  : Set the Block-Count
  -s<n>  : Set the Block-Size (Don't use both -b and -s)
  -r<n>  : Level of Redundancy (%%)
  -c<n>  : Recovery block count (Don't use both -r and -c)
  -f<n>  : First Recovery-Block-Number
  -u     : Uniform recovery file sizes
  -l     : Limit size of recovery files (Don't use both -u and -l)
  -n<n>  : Number of recovery files (Don't use both -n and -l)
  -m<n>  : Memory (in MB) to use
  -v [-v]: Be more verbose
  -q [-q]: Be more quiet (-q -q gives silence)
  --     : Treat all remaining CommandLine as filenames

If you wish to create par2 files for a single source file, you may leave
out the name of the par2 file from the command line.
sander@netbook:~$ 

[shypike]

I'm running a four disk array in RAID5 and get pretty decent read/write performance.

RAID5 is slower when writing (for obvious reasons).
Consider (if possible) to put temporary folders on a non-RAID disk.

[Headcase_Fargone]

I'm running a four disk array in RAID5 and get pretty decent read/write performance.

RAID5 is slower when writing (for obvious reasons).
Consider (if possible) to put temporary folders on a non-RAID disk.

Hrm, good point. Is there an easy way to set it up so that par2 unpacks the contents to the OS drive (running on an SSD) then moves the contents to the completed folder once it's done?

[shypike]

It's enough that you keep the "temporary download folder" on the SSD disk.
Unpacking from the SSD disk to the RAID disk is the optimal solution.
Unpacking from SSD to the same SSD and then to RAID, will be slower.
Also set an article cache of about 200M in Config->General. This will greatly reduce disk access
(and increase the life time of your SSD).