Re: 2.2.6_andrea2.bz2

Chuck Lever (cel@monkey.org)
Sun, 25 Apr 1999 14:29:12 -0400 (EDT)


On Sun, 25 Apr 1999, Andrea Arcangeli wrote:
> o smp lock profiling. It's also a config option (so no overhead if you
> are not interested to see how much your CPU are scaling well).

is there a nice way to find out *which* spinlocks are popular? i already
know that the 4-way is seeing a big performance hit -- i'd like to know
where.

> o i386 irq_desc cacheline aligned.

any chance this could make it into 2.2? it's a free 1% performance
improvement on SMP.

> o prune dcache before start swapping, the prune won't be a complete
> prune but will be in function of the priority and will scale nicely.
> Well the implementation it's not that clever but works fine here:
>
> - prune_dcache(0);
> + prune_dcache(dentry_stat.nr_unused / (priority+1));

this is a good idea -- it keeps the dcache hash table performing well;
i've actually measured some overall performance improvement. however, is
there a way to do this without a DIV operation?

> o rb-tree in the page cache (not per-inode rb but only one whole rb).

how about dcache too? :)

> 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?

- Chuck Lever

--
corporate:	<chuckl@netscape.com>
personal:	<chucklever@netscape.net> or <cel@monkey.org>

The Linux Scalability project: http://www.citi.umich.edu/projects/linux-scalability/

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