[bittorrent] Introductory/endgame algorithms

Olaf van der Spek olafvdspek at gmail.com
Thu Sep 29 05:23:27 EDT 2005


On 9/29/05, Elliott Mitchell <ehem at m5p.com> wrote:
> > I think it's the other way around, the common case being multiple files.
>
> To tell the truth, no idea. I'm mostly after Linux CD images which tend
> to be very large single files, I won't claim that is the majority. Other
> things I've seen tend to be multi-hundred megabyte files. There needs to
> be one more factor present to make this problematic, the file sizes need
> to not be a factor of your page size.

Only a single file needs to have a 'non-aligned' end to affect all
files following.
DVDs are frequently distributed as VIDEO_TS dir and I'm not sure if
all file ends are aligned there.

> With ISO images the block size is 2KB, so 50% chance of files being well
> aligned with 4KB pages; however I doubt it is common to have multiple ISO
> images in a single torrent. Do other commonly used files specify a
> particular alignment? Looking at a couple handy large files, all of them
> are multiples of 4KB in size. I can't guarentee other files are, but I
> imagine many formats will suggest a padding for the reason of performance
> (I note filesystems which actually pack the final non-blocksize element
> of a file together are rare, ReiserFS is the only one I know of).



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