Re: VFS 64-bit clean? Not yet (was Re: large-file-system)
chip@atlantic.net
Tue, 10 Feb 1998 09:36:37 -0500 (EST)
According to Rik van Riel:
> On Sun, 8 Feb 1998 chip@atlantic.net wrote:
> > Well, some people may have 64-bit-clean as their goal, but I'm
> > limiting my horizon to 41- or 42-bit-clean (32-bit block numbers, 512
> > byte or 1K blocks).
> >
> > It seems to me that 2048G or 4096G is enough for now, and if I try
> > to go bigger, then the "struct page" has to get bigger, and that's
> > a performance hit.
>
> It would also be a performance hit to have to recalculate
> the offset every time...
Just a left shift by a constant. Probably not even measurable.
> And exactly how much would the struct page grow?
Four bytes per page. In a 64M machine, that's 64K of kernel memory.
I think that's worth saving if possible.
--
Chip Salzenberg - a.k.a. - <chip@pobox.com>
"Nice shooting, Zanthar!" "Thanks, Denise." // MST3K
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