Is the Process Priority Setting Counterintuitive?

[Muad'Dib]

I just finished a backup with ImageWin 2.71 and since I wasn't doing anything else critical with the computer at the time, I changed the Process Priority setting to "Above Normal" (ostensibly to speed things up a bit). The backup itself seemed to go fine, but when it started doing a byte-for-byte validation it seemed to be going slower than I expected. So I then decided to change the Process Priority to "High", and that didn't seem to help. So just for the heck of it, I set the Priority to "Low" and that did the trick, the validation finished much faster than the estimated time remaining at the time I changed the Priority setting, and continued to decrement pretty rapidly (while under the Above Normal & High settings, the estimated time remaining seemed to be hovering around the same value for quite awhile). Throughout all this, the MiB remaining and transferred numbers continued to change in the right direction, so the program hadn't locked up, it was just working more slowly than I wanted (until I changed the Priority to Low).

This is the first time I've ever bothered to change this setting, so I'm not sure if it's a fluke or not. If not, then aren't the settings the opposite of what most people would expect? If I choose "High", I'm expecting that I'm making ImageWin the most important process (and all my other programs will suffer accordingly), and if I choose "Low", then ImageWin will take a backseat to other programs I consider more important at the time.

Unfortunately the documentation mentions nothing about the meaning of these settings. It just explains how to set them, whether interactively (as I did), or as a command line option. Also, though I've only registered on the forum last year, I've been using Image for Windows (and for DOS) for many years, so I'm very familiar with the program (just not this setting).

So is this a bug or a (weird) design decision?

[TeraByte Support]

It's all handled by Windows, it just allows you to change the cpu process
priority (same as if you went in and manually changed the process priority).

See
http://msdn.microsoft.com/en-us/library/windows/desktop/ms685100%28v=vs.85%29.aspx


"Muad'Dib" wrote in message news:2604@public.image...

I just finished a backup with ImageWin 2.71 and since I wasn't doing
anything else critical with the computer at the time, I changed the Process
Priority setting to "Above Normal" (ostensibly to speed things up a bit).
The backup itself seemed to go fine, but when it started doing a
byte-for-byte validation it seemed to be going slower than I expected. So I
then decided to change the Process Priority to "High", and that didn't seem
to help. So just for the heck of it, I set the Priority to "Low" and that
did the trick, the validation finished much faster than the estimated time
remaining at the time I changed the Priority setting, and continued to
decrement pretty rapidly (while under the Above Normal & High settings, the
estimated time remaining seemed to be hovering around the same value for
quite awhile). Throughout all this, the MiB remaining and transferred
numbers continued to change in the right direction, so the program hadn't
locked up, it was just working more slowly than I wanted (until I changed
the Priority to Low).

This is the first time I've ever bothered to change this setting, so I'm not
sure if it's a fluke or not. If not, then aren't the settings the opposite
of what most people would expect? If I choose "High", I'm expecting that I'm
making ImageWin the most important process (and all my other programs will
suffer accordingly), and if I choose "Low", then ImageWin will take a
backseat to other programs I consider more important at the time.

Unfortunately the documentation mentions nothing about the meaning of these
settings. It just explains how to set them, whether interactively (as I
did), or as a command line option. Also, though I've only registered on the
forum last year, I've been using Image for Windows (and for DOS) for many
years, so I'm very familiar with the program (just not this setting).

So is this a bug or a (weird) design decision?

[Muad'Dib]

Maybe because I'm runnning on barely any sleep, but that link doesn't explain to me what choosing the IFW Process Priority is supposed to do.

When I choose a Process Priority of "High" in IFW, I assumed that this would give IFW the highest priority (this seems very logical to me), but it seems to be doing the opposite.

Is it doing the opposite? Please simply answer the above question, I've only tried this once, so maybe my experience wasn't normal.

Now if my assumption is correct, then I have the following suggestion:

If choosing "High" causes IFW to run more slowly, then maybe the description should be changed from "Process Priority" to something like "Background Priority" or "Background Process Priority"

Or even better (from a naive user point of view), maybe the priority levels should be reversed, so that choosing "High" gives IFW the highest priority, and choosing "Low" gives IFW the lowest priority. And then of course to make things totally clear, change the label to "IFW Priority"

[TeraByte Support]

high gives it more cpu time.
low gives it less cpu time.


"Muad'Dib" wrote in message news:2607@public.image...

Maybe because I'm runnning on barely any sleep, but that link doesn't
explain to me what choosing the IFW Process Priority is supposed to do.

When I choose a Process Priority of "High" in IFW, I assumed that this would
give IFW the highest priority (this seems very logical to me), but it seems
to be doing the opposite.

Is it doing the opposite? Please simply answer the above question, I've only
tried this once, so maybe my experience wasn't normal.

Now if my assumption is correct, then I have the following suggestion:

If choosing "High" causes IFW to run more slowly, then maybe the description
should be changed from "Process Priority" to something like "Background
Priority" or "Background Process Priority"

Or even better (from a naive user point of view), maybe the priority levels
should be reversed, so that choosing "High" gives IFW the highest priority,
and choosing "Low" gives IFW the lowest priority. And then of course to make
things totally clear, change the label to "IFW Priority"

[Muad'Dib]

TeraByte Support wrote:
> high gives it more cpu time.
> low gives it less cpu time.
>

1) So by "it" you mean Image for Windows? I'm not being sarcastic, I just want to be absolutely sure I'm understanding your answer.

2a) If yes to question #1, then what do you think happened with my experience (noticeable speed increase when I set Process Priority to Low)? I realize it might be a wrong observation on my part, but it sure didn't seem like it. And if I get the time, I'll try to replicate it with smaller backups, repeating it with both the High and Low setting and benchmark both settings.

2b) If no to question #1, then do you think it makes sense to change the wording and/or settings in the program to make it more logical?

[DrTeeth]

My understanding, and I may be wrong, is that this type of setting
only makes a difference if something else (program or background
process) is trying to use the CPU as well. If nothing else is going on
there will not be any difference. personally, the setting does not
make much/any difference here as I think that my personal bottleneck
is the I/O disk writing process.

For your tests, it will be difficult to ensure that a couple of tests
are being run under identical conditions. I would also imagine that
'high' and 'low' are relative terms and I can see a situation where a
'low' setting could easily be faster than a 'high' setting.

If I am talking warm male-cow droppings, I'm sure somebody will
correct me.
--

Cheers

DrT
______________________________
We may not be able to prevent the stormy times in
our lives; but we can always choose to dance
in the puddles (Jewish proverb).

[Muad'Dib]

=============================================
DrTeeth wrote:
I would also imagine that 'high' and 'low' are relative terms and I can see a situation where a 'low' setting could easily be faster than a 'high' setting.
==============================================

This is why I'm still waiting for a clear, unambiguous response, as to what setting does what. Once I know how it's SUPPOSED to work, I can run some simple tests to make sure my copy is behaving properly (or I'll already know it's behaving the way it's supposed to!).

Thanks anyway Dr T!

[DrTeeth]

On Tue, 19 Jun 2012 12:09:37 PDT, just as I was about to take a herb,
Muad'Dib disturbed my reverie and wrote:

>Thanks anyway Dr T!

Good luck in your quest for enlightenment !
--

Cheers

DrT
______________________________
We may not be able to prevent the stormy times in
our lives; but we can always choose to dance
in the puddles (Jewish proverb).

[Muad'Dib]

DrTeeth wrote:
> Good luck in your quest for enlightenment !
============================================
Thanks. Unfortunately, it seems my quest is being ignored by TeraByte Support. Maybe someday my latest question (the 5th post in this thread) will be answered clearly by someone who knows.

[TeraByte Support]

The way windows handles priorities is here:
http://msdn.microsoft.com/en-us/library/windows/desktop/ms685100%28v=vs.85%29.aspx

If you had it at high priority, it would normally get more cpu time from the
scheduler than other things, (taking away time from other things).

The CPU priority (that option you changed and explained above) is not to be
confused with IO priority. During backup if another process is requesting a
priority 0 (low priority file operation) IO operation it will get delayed
since there is a lot of file activity writing data to the file at normal IO
priority (unless you used the command line switch to change io priority).


"Muad'Dib" wrote in message news:2643@public.image...

DrTeeth wrote:
> Good luck in your quest for enlightenment !
============================================
Thanks. Unfortunately, it seems my quest is being ignored by TeraByte
Support. Maybe someday my latest question (the 5th post in this thread) will
be answered clearly by someone who knows.