Messages in this thread | | | Date | Sat, 7 Jul 2007 12:25:02 +0200 | From | Andrea Arcangeli <> | Subject | Re: RFC: CONFIG_PAGE_SHIFT (aka software PAGE_SIZE) |
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On Sat, Jul 07, 2007 at 05:01:57PM +1000, Paul Mackerras wrote: > Andrea Arcangeli writes: > > > So my whole idea is to once and for all to decuple the size of the > > pte-entry (4k on x86/amd64) with the page allocator granularity. The > > HARD_PAGE_SHIFT will be 4k still, the common code PAGE_SIZE will be > > variable and configurable at compile time with CONFIG_PAGE_SHIFT. > > How does the page cache work with your scheme? For example if I have > 1000 1kB files cached in the page cache, and 16k PAGE_SIZE, does that > use up 4M, or 16M?
It uses 16M of course. Like I said before:
This whole issue is really a pure tradeoff between memory consumption and I/O and CPU performance (and for the dvd-ram and xfs also a way to
The CONFIG_PAGE_SHIFT allows you to ship a "monster" kernel for db usage with hundred gigs of ram, with 64k page size and 64k blocksize, getting the whole advantages. We of course must make sure that CONFIG_PAGE_SHIFT=12 doesn't provide any slowdown.
Then us mere mortals will enjoy running with 8k page size too, with our 2-4G of ram. I used 8k page size with an alpha workstation back in 2000 and I didn't feel any substantial ram waste, I had about 2G of ram. Ok, now the kernel is larger, but even git learnt using packs ;) - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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