Re: [PATCH] make radix tree gang lookup faster by using a bitmapsearch

[Nick Piggin]

James Bottomley wrote:

> On Tue, 2005-08-30 at 10:56 +1000, Nick Piggin wrote:
>
>
> > Gang lookup is mainly used on IO paths but also on truncate,
> > which is a reasonably fast path on some workloads (James,
> > this is my suggestion for what you should test - truncate).
>
> Actually, I don't think I can test this.  In order to show a difference
> between index 5 and index 6 on 32 bit, I'd have to deal with files > 4GB
> in size.  My 32 bit machines are the voyagers and only have 4GB discs.
>
> The machine with all the huge discs, is, naturally, ia64.

Sorry, I meant for testing your gang lookup speedups.

For testing regular lookups, yeah that's more difficult. For a
microbenchmark you can use sparse files, which can be a good
trick for testing pagecache performance without the IO.

Nick


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