[syslinux] [RFC] COMBOOT: readdir: st_mode or d_type

Thomas Schmitt scdbackup at gmx.net
Tue Mar 3 11:48:16 PST 2009


Hi,

Gene Cumm wrote:
> The most important thing to return is the filename.
> ISO9660 dirents contain name, size, type and any other attributes.

ISO 9660 filenames are quite mediocre.
The attributes of ISO 9660 (aka ECMA-119) do not
match well with struct stat.

If you plan to follow the default behavior of
mounted ISO 9660 on e.g. Linux then you will be 
interested in eventual Rock Ridge entries which
give long name, stat(2) attributes, symbolic link
target.


> [...] in the case of a cache miss.

The Rock Ridge entries may be larger than the
System Use Area in the ISO directory entry.
In that case they are continued in a data block
outside the directory entry (Continuation Area,
pointed to by SUSP entry CE).
This redirection makes cache misses more likely.
Expect at least two groups of read positions which
are used frequently and are several hundred KB apart.

libisoburn shows sufficient performance with
16 cache tiles of 128 kB each. But we have of
course a different situation when we load a tree
of 1e5 files into memory. I assume you mainly
expect trees of a few hundred files. At least that's
what i see with bootable CD or DVD.


Have a nice day :)

Thomas




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