Re: [PATCH 06/33] readahead: refactor __do_page_cache_readahead()

[Andrew Morton]

Wu Fengguang <wfg@xxxxxxxxxxxxxxxx> wrote:
>
> Add look-ahead support to __do_page_cache_readahead(),
> which is needed by the adaptive read-ahead logic.

You'd need to define "look-ahead support" before telling us you've added it ;)

> @@ -302,6 +303,8 @@ __do_page_cache_readahead(struct address
>  			break;
>  		page->index = page_offset;
>  		list_add(&page->lru, &page_pool);
> +		if (page_idx == nr_to_read - lookahead_size)
> +			__SetPageReadahead(page);
>  		ret++;
>  	}

OK.  But the __SetPageFoo() things still give me the creeps.


OT: look:

		read_unlock_irq(&mapping->tree_lock);
		page = page_cache_alloc_cold(mapping);
		read_lock_irq(&mapping->tree_lock);

we should have a page allocation function which just allocates a page from
this CPU's per-cpu-pages magazine, and fails if the magazine is empty:

		page = 	alloc_pages_local(mapping_gfp_mask(x)|__GFP_COLD);
		if (!page) {
			read_unlock_irq(&mapping->tree_lock);
			/*
			 * This will refill the per-cpu-pages magazine
			 */
			page = page_cache_alloc_cold(mapping);
			read_lock_irq(&mapping->tree_lock);
		}

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