AW: what is the bottleneck when copying file from CD?

Tiemo Hollmann TB toolbook at kestner.de
Fri Jan 23 03:25:01 EST 2009


Just to give you a feedback of my further tests.

1. The main performance difference is between Notebooks (average: 2,4MB/s)
and Desktops (average: 4,2MB/s), because of HW differences.
2. The very slow performance of the MacBook was because of a CD burned on
Win. When burning the same datas on the Mac, the performance was almost
exact the same between a comparable Win Notbook and MacBook
3. The chunk size for read/write has between 4096 bytes and 10MB almost no
significant performance difference. Lower than 4096 bytes the performance
decreased dramatically, with a chunk size of 512 bytes I had only 0,4MB/s.
Probably because her the performance part of my repeat loop comes into
account.

My conclusion is, I'll go with a chunk size of 4096 bytes and will tell my
customers, that the installation of my 7GB will take between 30 and 90 min,
depending on the performance of their machines. (I even had a betatester,
where it took 140min on a 3 year old Win Notebook, but I hope it is a single
outlier)

Thanks Luis and Florian to point me to the right direction.
Tiemo


> -----Ursprüngliche Nachricht-----
> Von: use-revolution-bounces at lists.runrev.com [mailto:use-revolution-
> bounces at lists.runrev.com] Im Auftrag von Tiemo Hollmann TB
> Gesendet: Mittwoch, 21. Januar 2009 13:05
> An: 'How to use Revolution'
> Betreff: what is the bottleneck when copying file from CD?
> 
> Hello,
> 
> I have to copy about 7 GB in 6 zip files from DVD-ROM to HD.
> 
> I do it by a repeat loop with read - write - see below.
> 
> 
> 
> Because I experienced very big performance differences on different
> machines, I made extensive tests on different machines and different read
> chunk sizes in the repeat loop.
> 
> First I experienced that the chunk size for reading has almost no
> influence
> on the total time. Tested with a chunkSize of 100K, 1MB, 10MB, 100MB.
> 
> But I experienced very big differences on different machines. Total
> copying
> time for 6,7 GB varies between 27min on a PC Desktop (Core 2, 2,66Ghz,
> 2GB),
> 49 min On a Vista Notebook (Core 2 Duo, 1,86 Ghz, 2GB) and 93min on a
> MacBook (Core 2 Duo, 2,2 Ghz, 2GB), what meant a put through of 4,1 MB/s
> on
> the PC and 1,2 MB/s on the Mac.
> 
> 
> 
> I am not the hardware or system guy, so can anybody shed some light on
> these
> differences. What is the bottleneck and is there anything I can do in my
> script, or do I have to tell my customers "Installation time can vary
> between half an hour and two hours :-( ." and it is just like it is?
> 
> 
> 
> Thanks for any hint or experiences
> 
> Tiemo
> 
> 
> 
> 
> 
> The code snipped is:
> 
>     open file tQuellFile for binary read
> 
>     open file tZielFile for binary write
> 
>     repeat until it is empty
> 
>         read from file tQuellFile for gChunkSize #a global for testing
> 
>         if it is not empty then
> 
>             write it to file tZielFile
> 
>         end if
> 
>         add gChunkAdd to tMB
> 
>         set the thumbpos of sb "Progress" to tMB
> 
>         put tMB && "MB von gesamt ca." && gGesamtSize && "MB kopiert..."
> into fld "fldMB" # progress in MB
> 
>         if the uCancel of this stack is true then
> 
>             close file tQuellFile
> 
>             close file tZielFile
> 
>             answer "Abbruch"
> 
>             exit to top
> 
>         end if
> 
>         wait 1 millisecs with messages # wait 0 didn't worked, no click on
> a
> button was accepted
> 
>     end repeat
> 
> 
> 
> 
> 
> 
> 
> 
> 
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