Messages in this thread | | | Date | Sun, 30 May 1999 10:47:06 -0700 (PDT) | From | Linus Torvalds <> | Subject | Re: [PATCH] cache large files in the page cache |
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On 30 May 1999, Eric W. Biederman wrote: > > LT> Indeed. An dI would suggest that the shift be limited to at most 9 anyway: > LT> right now I applied the part that disallows non-page-aligned offsets, but > LT> I think that we may in the future allow anonymous mappings again at finer > LT> granularity (somebody made a really good argument about wine for this). > > I'd love to hear the argument. Something that would negate the disadvantage > of ntuple buffering, and the need for reverse page maps, and isn't portable.
Wine.
Mapping windows binaries in a Linux address space.
Portability is a non-issue: this would only work on a 386, and only on Linux anyway (MAYBE on other architectures Wine supports, but that's their problem).
Windows binaries are _not_ nicely aligned like the Linux ones. They are often 512-byte aligned.
Yes, we can read them in. That is slow as hell, and doesn't allow sharing. Bad.
> Well, currectly supporting non-aligned mappings needs more than just a > few extra bits. The code to update all mappings on write, and the > ability to ensure that a given byte is only faulted in for a single > offset at a time. (Admittedly if everything is a read mapping you > can be a smidge more lax).
We would not guarantee write coherency for anything but the page-aligned case.
Linus
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