Re: Ext2fs patch

[Yoshinori K. Okuji]

On Tuesday 28 October 2003 21:46, Marco Gerards wrote:
> When reading the first block from a partition you won't read the first
> block.  Normally there is no problem, but with util/i386/pc/biosdisk.c
> the partition is accessed separately and that means a negative sector
> number.

I understand.

> I wonder if it is wise to read blocks before the block you want to
> read.  I think this usually doesn't make much sense.  Usually
> filesystems are optimized to read forwards.

That's right. The current implementation is just for simplicity (in other 
words, because I was lazy), so it is not perfect from performance point of 
view.

However, I suspect that there would be no gain from making the cache system 
work better by always reading blocks forwards. Normally, reading some blocks 
at a time is quite fast (i.e. it does not differ from reading a single block 
very much). And, even if it reads some unnecessary blocks, when you read a 
file sequentially, the overhead would be negligible. As PUPA reads at most 8 
blocks at a time, if you read more than 800 blocks sequentially, the overhead 
is less 1%.

> The new patch is included in this mail.  I've also updated the
> copyright years, I forgot some in my previous patch *blush*.

Now is the time to commit. :)

Okuji