Re: [RFC] Reorganizing structs to save space
From: Matt Mackall
Date: Tue Apr 03 2007 - 17:43:26 EST
On Tue, Apr 03, 2007 at 09:28:48AM -0300, Arnaldo Carvalho de Melo wrote:
> module 16960 16848 112
That's huge.
> struct module_ref ref[255]; /* 480 16320 */
Huh. That's this:
struct module_ref
{
local_t count;
} ____cacheline_aligned;
This is horrible. Surely there's some way to do better than a
cacheline per module per possible CPU. We should only need 4 bytes per
module per online CPU.
And really, about the only case where we actually care about cacheline
bouncing here at all is on modules that do this per-packet. Just about
everyone else can get by with 4 bytes per module total.
--
Mathematics is the supreme nostalgia of our time.
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