Re: 2.2.6_andrea2.bz2

Andi Kleen (ak@muc.de)
Mon, 26 Apr 1999 15:45:24 +0200


On Mon, Apr 26, 1999 at 10:05:56AM +0200, Eric W. Biederman wrote:
> >>>>> "AA" == Andrea Arcangeli <andrea@e-mind.com> writes:
>
> >>> o update_shared_mappings (will greatly improve performances while
> >>> writing from many task to the same shared memory).
> >>
> >> do you have performance numbers on this?
>
> AA> The performance optimization can be huge.
>
> AA> The reason this my code is not in the kernel is not because it's buggy but
> AA> simple because there are plans for 2.3.x (no-way for 2.2.x) to allow the
> AA> file cache to be dirty (to cache also writes and not only read in the page
> AA> cache).
>
> Andrea. The plan (at least my plan) is not to have 2 layers of buffers.
> Instead it is to do all of the caching (except for perhaps superblocks, and their
> kin in the page cache). brw_page will be used for both reads and writes, with
> anonymouse buffer heads (at least for a start).

Stupid question: do you plan to cache fs metadata in the page cache too?
If yes, it is rather wasteful to use a 4K page for the usually block sized
directories and other fs data like indirect blocks. How do you plan to
address this problem?

-Andi

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