From: Andrew Morton <akpm@linux-foundation.org>
To: Michel Lespinasse <walken@google.com>
Cc: riel@redhat.com, peterz@infradead.org, daniel.santos@pobox.com,
aarcange@redhat.com, dwmw2@infradead.org, linux-mm@kvack.org,
linux-kernel@vger.kernel.org, torvalds@linux-foundation.org
Subject: Re: [PATCH v3 3/9] rbtree: place easiest case first in rb_erase()
Date: Mon, 20 Aug 2012 15:28:02 -0700 [thread overview]
Message-ID: <20120820152802.272ec736.akpm@linux-foundation.org> (raw)
In-Reply-To: <1345500331-10546-4-git-send-email-walken@google.com>
On Mon, 20 Aug 2012 15:05:25 -0700
Michel Lespinasse <walken@google.com> wrote:
> In rb_erase, move the easy case (node to erase has no more than
> 1 child) first. I feel the code reads easier that way.
Well. For efficiency we should put the commonest case first. Is that
the case here?
> --- a/lib/rbtree.c
> +++ b/lib/rbtree.c
> @@ -368,17 +368,28 @@ static void __rb_erase_color(struct rb_node *node, struct rb_node *parent,
>
> void rb_erase(struct rb_node *node, struct rb_root *root)
> {
> - struct rb_node *child, *parent;
> + struct rb_node *child = node->rb_right, *tmp = node->rb_left;
Coding style nit: multiple-definitions-per-line makes it harder to
locate a particular definition, and from long experience I can assure
you that it makes management of subsequent overlapping patches quite a
lot harder. Also, one-definition-per-line gives room for a nice little
comment, and we all like nice little comments.
Also, "tmp" is a rotten name. Your choice of an identifier is your
opportunity to communicate something to the reader. When you choose
"tmp", you threw away that opportunity. Should it be called "left"?
--- a/lib/rbtree.c~rbtree-place-easiest-case-first-in-rb_erase-fix
+++ a/lib/rbtree.c
@@ -368,12 +368,13 @@ static void __rb_erase_color(struct rb_n
void rb_erase(struct rb_node *node, struct rb_root *root)
{
- struct rb_node *child = node->rb_right, *tmp = node->rb_left;
+ struct rb_node *child = node->rb_right
+ struct rb_node *tmp = node->rb_left;
struct rb_node *parent;
int color;
if (!tmp) {
- case1:
+case1:
/* Case 1: node to erase has no more than 1 child (easy!) */
parent = rb_parent(node);
_
--
To unsubscribe, send a message with 'unsubscribe linux-mm' in
the body to majordomo@kvack.org. For more info on Linux MM,
see: http://www.linux-mm.org/ .
Don't email: <a href=mailto:"dont@kvack.org"> email@kvack.org </a>
next prev parent reply other threads:[~2012-08-20 22:28 UTC|newest]
Thread overview: 16+ messages / expand[flat|nested] mbox.gz Atom feed top
2012-08-20 22:05 [PATCH v3 0/9] faster augmented rbtree interface Michel Lespinasse
2012-08-20 22:05 ` [PATCH v3 1/9] rbtree test: fix sparse warning about 64-bit constant Michel Lespinasse
2012-08-20 22:05 ` [PATCH v3 2/9] rbtree: add __rb_change_child() helper function Michel Lespinasse
2012-08-20 22:17 ` Andrew Morton
2012-08-23 12:05 ` Jan Engelhardt
2012-08-23 13:08 ` David Woodhouse
2012-09-26 22:34 ` Daniel Santos
2012-09-26 22:43 ` Andrew Morton
2012-08-20 22:05 ` [PATCH v3 3/9] rbtree: place easiest case first in rb_erase() Michel Lespinasse
2012-08-20 22:28 ` Andrew Morton [this message]
2012-08-20 22:05 ` [PATCH v3 4/9] rbtree: handle 1-child recoloring in rb_erase() instead of rb_erase_color() Michel Lespinasse
2012-08-20 22:05 ` [PATCH v3 5/9] rbtree: low level optimizations in rb_erase() Michel Lespinasse
2012-08-20 22:05 ` [PATCH v3 6/9] rbtree: augmented rbtree test Michel Lespinasse
2012-08-20 22:05 ` [PATCH v3 7/9] rbtree: faster augmented rbtree manipulation Michel Lespinasse
2012-08-20 22:05 ` [PATCH v3 8/9] rbtree: remove prior augmented rbtree implementation Michel Lespinasse
2012-08-20 22:05 ` [PATCH v3 9/9] rbtree: add RB_DECLARE_CALLBACKS() macro Michel Lespinasse
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=20120820152802.272ec736.akpm@linux-foundation.org \
--to=akpm@linux-foundation.org \
--cc=aarcange@redhat.com \
--cc=daniel.santos@pobox.com \
--cc=dwmw2@infradead.org \
--cc=linux-kernel@vger.kernel.org \
--cc=linux-mm@kvack.org \
--cc=peterz@infradead.org \
--cc=riel@redhat.com \
--cc=torvalds@linux-foundation.org \
--cc=walken@google.com \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).