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SubjectRe: multiply files in one (was GNU/Linux stance by Richard Stallman)
Larry McVoy wrote:
> : > Your still missing the performance implications. In many, many typical
> : > cases (and this will become more and more true as memory gets cheaper),
> : > it would be far faster to eat the whole tarball and explode it into a
> : > bunch of in memory files even to get just a few of the files. Work
> : > through the math - if each file costs you a seek, you only need to get
> : > to 2-3 files before it would be faster to get 'em all.
> :
> : Hm. But do we need a special FS for this? In theory, isn't this
> : covered by a sufficiently aggressive read-ahead mechanism at the block
> : layer and in the drive itself? If the HDD reads in a whole sector into
> : its cache, that will contain a fair number of small files.
>
> THINK. You guys aren't THINKING. It is very FRUSTRATING.
>
> If you have 200 small files and you have to go get 200 inodes and 200 blocks
> to read them in, the inodes and the blocks aren't next to each other, that's
> 400 disk transactions instead of 1. THINK. PLEASE. This is the third time
> I've gone over this point.

Just to help your sanity, I hear you Larry, and agree with what you are
saying.

Of course, I'm thinking a userfs solution would work here.

sidenote: Does anyone know if there is a workable user fs patch set
anywheres for 2.2.x?

I had something like this going under a pseudo win95 userfs a while
back, and am working on a reimplementaion that will work both on win95
and on linux. For the stuff I'm doing at least userfs would be
cleanest. I'm thinking keeping the code for tar/gzip/bzip2/zip/... out
of the kernel would be a good thing.

Of course you get the cool side benefit of doing: cd foo.tar

Steve

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