[En-Nut-Discussion] Improvement for faster mounting of large SD cards
uprinz2 at netscape.net
Wed Jan 20 08:34:29 CET 2010
On Tue, 19 Jan 2010 09:33:52 +0100, "Rob van Lieshout \(PragmaLab\)"
<info at pragmalab.nl> wrote:
> Hello Malte
>> I am using a 4GB SD card together with Nut/OS. Unfortunately, mounting
>> a volume took several minutes.
> Using up to 8GB SD-HC cards, we have to same problem regarding the long
> mounting time. Since the number of free clusters is only needed when you
> start write operations, I slightly modified the code so that the free
> clusters are not counted during the mount process (that now takes less
> a second on a 14.57 MHz Mega256). The first time the card is asked to
> data, the clusters are counted, which indeed takes a long time with large
> capacity cards. It's not really an optimization, just a way to make
> less annoying for the user.
An optimization that may be put into Nut/OS could be to control the free
cluster counting via ioctl(). If we could implement a control that
configures for counting clusters or not before mounting would be a nice
That would improve speed for all using the card for read only.
Then we should try an improvement for those who need to write a card.
I don't see that counting free clusters in background is an improvement, as
one needs to wait for that information before writing, regardless if it's
calculated in your task or in a parallel one.
Best regards, Ulrich
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