[Qt-embedded-interest] long-term delay for QDir::entryList(), QDir::count() for directory located on USB stick

[Markus Franke]

I just figured out that the problem only occurs in case the cluster size 
of the FAT32 filesystem on the 4GByte USB stick is 4 KByte. 
If I change the cluster size to 32 KByte everything works fine.
By the way, same applies for USB sticks from other vendors.

Any comments on this?

Mit freundlichen Grüßen / Best regards

Markus Franke
Entwicklung/ Development

SebaKMT
Hagenuk KMT Kabelmesstechnik GmbH
Röderaue 41
01471 Radeburg / Germany
Reg.Gericht (01067 Dresden) HRB 12567
Geschäftsf.: Dr. Max Iann

Phone +49 (0)35208 84 29142
Fax      +49 (0)35208 84 29249

e-mail: franke.m at sebaKMT.com
web: http//www.sebaKMT.com

> Dear all,

> this message has already been on qt-interest but I just figured out that 

> it just applies (as far as I know) for Qt Embedded 4.5.0.
>
> I am observing long runtimes (around 50 seconds) for the functions 
> QDir::entryList() and QDir::count() when the directory is located on an 
> USB stick with VFAT filesystem. The long-term delay only occurs once 
after 
> the USB stick has been mounted for the first time. Subsequent calls 
> complete within a few seconds (one or two) which is alright for me.
>
> Here is some sample code which doesn't work for me:
>
> ---snip---
> QDir directory("/USB");
> directory.setNameFilters(QStringList("*.img"));
> directory.setFilter(QDir::NoDotAndDotDot | QDir::NoSymLinks | 
> QDir::Files);
>
> // This takes about 50 seconds when called for the first time
> qDebug("count = %d", directory.count());
> ---snap---
>
> The USB stick get's recognized as a USB 1.1 device and I am on a Linux 
2.6 
> system. I am using Qt Embedded 4.5.0
>
> Mit freundlichen Grüßen / Best regards
>
> Markus Franke
> Entwicklung/ Development
>
> SebaKMT
> Hagenuk KMT Kabelmesstechnik GmbH
> Röderaue 41
> 01471 Radeburg / Germany
> Reg.Gericht (01067 Dresden) HRB 12567
> Geschäftsf.: Dr. Max Iann
> 
> Phone +49 (0)35208 84 29142
> Fax      +49 (0)35208 84 29249
> 
> e-mail: franke.m at sebaKMT.com
> web: http//www.sebaKMT.com
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