From: Andrew Morton <akpm@linux-foundation.org>
To: Wu Fengguang <fengguang.wu@intel.com>
Cc: Vladislav Bolkhovitin <vst@vlnb.net>,
LKML <linux-kernel@vger.kernel.org>
Subject: Re: [PATCH 1/3] radix-tree: add radix_tree_prev_hole()
Date: Sun, 12 Apr 2009 10:29:52 -0700 [thread overview]
Message-ID: <20090412102952.0dd377d6.akpm@linux-foundation.org> (raw)
In-Reply-To: <20090412072052.457214378@intel.com>
On Sun, 12 Apr 2009 15:19:51 +0800 Wu Fengguang <fengguang.wu@intel.com> wrote:
> +unsigned long radix_tree_prev_hole(struct radix_tree_root *root,
> + unsigned long index, unsigned long max_scan)
> +{
> + unsigned long i;
> +
> + for (i = 0; i < max_scan; i++) {
> + if (!radix_tree_lookup(root, index))
> + break;
> + index--;
> + if (index == LONG_MAX)
> + break;
> + }
> +
> + return index;
> +}
argh. This is about as inefficient as we could possibly make it :(
Really, this function should dive into radix-tree internals and walk
individual radix_tree_node.slots[] arrays. And heck, it can peek at
radix_tree_node.count and _bypass_ entire nodes, too.
next prev parent reply other threads:[~2009-04-12 17:31 UTC|newest]
Thread overview: 14+ messages / expand[flat|nested] mbox.gz Atom feed top
2009-04-12 7:19 [PATCH 0/3] context readahead for concurrent IO take 2 Wu Fengguang
2009-04-12 7:19 ` [PATCH 1/3] radix-tree: add radix_tree_prev_hole() Wu Fengguang
2009-04-12 17:29 ` Andrew Morton [this message]
2009-04-13 13:44 ` Wu Fengguang
2009-04-12 7:19 ` [PATCH 2/3] readahead: move the random read case to bottom Wu Fengguang
2009-04-12 7:19 ` [PATCH 3/3] readahead: introduce context readahead algorithm Wu Fengguang
2009-04-12 8:48 ` Ingo Molnar
2009-04-12 12:35 ` Wu Fengguang
2009-04-16 17:12 ` Vladislav Bolkhovitin
2009-04-15 3:43 ` Jeff Moyer
2009-04-15 4:43 ` Wu Fengguang
2009-04-15 17:55 ` Jeff Moyer
2009-04-27 4:48 ` Wu Fengguang
-- strict thread matches above, loose matches on Subject: below --
2009-04-10 13:12 [PATCH 0/3] context readahead for concurrent IO Wu Fengguang
2009-04-10 13:12 ` [PATCH 1/3] radix-tree: add radix_tree_next_hole() Wu Fengguang
2009-04-10 13:31 ` [PATCH 1/3] radix-tree: add radix_tree_prev_hole() Wu Fengguang
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