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SubjectRe: [PATCH] page coloring for 2.5.59 kernel, version 1
On Mon, Jan 27, 2003 at 07:57:36PM -0800, William Lee Irwin III wrote:
> set_num_colors() needs to go downstairs under arch/ Some of the
> current->pid checks look a bit odd esp. for GFP_ATOMIC and/or
> in_interrupt() cases. I'm not sure why this is a config option; it
> should be mandatory. I also wonder about the interaction of this with
> the per-cpu lists. This may really want to be something like a matrix
> with (cpu, color) indices to find the right list; trouble is, there's a
> high potential for many pages to be trapped there. mapnr's (page -
> zone->zone_mem_map etc.) are being used for pfn's; this may raise
> issues if zones' required alignments aren't num_colors*PAGE_SIZE or
> larger. proc_misc.c can be used instead of page_color_init(). ->free_list
> can be removed. get_rand() needs locking, per-zone state. Useful stuff.

Hmm, actually the mapnr's as physical pfn's are broken with
MAP_NR_DENSE(), though existing boxen probably luck out. The RNG uses
an integer multiply which may be slow on various cpus, and I wouldn't
mind either a stronger or better documented RNG algorithm. ->color_init
is basically a bitflag, and ->target_color has a very limited range.
sizeof(task_t) needs to be small, could you fold that stuff into
->flags or ->thread_info?

-- wli
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