Re: [PATCH] slob: poor man's NUMA, take 2.

[Matt Mackall <mpm@selenic.com>]

On Wed, Jun 13, 2007 at 12:12:03PM +0900, Paul Mundt wrote:
> Here's an updated copy of the patch adding simple NUMA support to SLOB,
> against the current -mm version of SLOB this time.
> 
> I've tried to address all of the comments on the initial version so far,
> but there's obviously still room for improvement.
> 
> This approach is not terribly scalable in that we still end up using a
> global freelist (and a global spinlock!) across all nodes, making the
> partial free page lookup rather expensive. The next step after this will
> be moving towards split freelists with finer grained locking.
> 
> The scanning of the global freelist could be sped up by simply ignoring
> the node id unless __GFP_THISNODE is set. This patch defaults to trying
> to match up the node id for the partial pages (whereas the last one just
> grabbed the first partial page from the list, regardless of node
> placement), but perhaps that's the wrong default and should only be done
> for __GFP_THISNODE?

Hmmm. There's not a whole lot that uses __GFP_THISNODE. Dunno.
 
> +static inline void *slob_new_page(gfp_t gfp, int order, int node)
> +{
> +	void *page;
> +
> +#ifdef CONFIG_NUMA
> +	if (node != -1)
> +		page = alloc_pages_node(node, gfp, order);
> +	else
> +#endif
> +		page = alloc_pages(gfp, order);
> +
> +	if (!page)
> +		return NULL;
> +
> +	return page_address(page);

We might want to leave the inlining decision here to the compiler. The
ifdef may change that decision..

> -void *__kmalloc(size_t size, gfp_t gfp)
> +static void *slob_node_alloc(size_t size, gfp_t gfp, int node)

See my comment in the last message.

-- 
Mathematics is the supreme nostalgia of our time.

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