From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from psmtp.com (na3sys010amx134.postini.com [74.125.245.134]) by kanga.kvack.org (Postfix) with SMTP id A16CB6B004D for ; Fri, 27 Jul 2012 17:55:48 -0400 (EDT) Received: by ggm4 with SMTP id 4so4432560ggm.14 for ; Fri, 27 Jul 2012 14:55:47 -0700 (PDT) MIME-Version: 1.0 In-Reply-To: <1343419466.32120.50.camel@twins> References: <1342787467-5493-1-git-send-email-walken@google.com> <1342787467-5493-5-git-send-email-walken@google.com> <1343419466.32120.50.camel@twins> Date: Fri, 27 Jul 2012 14:55:46 -0700 Message-ID: Subject: Re: [PATCH 4/6] rbtree: faster augmented insert From: Michel Lespinasse Content-Type: text/plain; charset=ISO-8859-1 Sender: owner-linux-mm@kvack.org List-ID: To: Peter Zijlstra Cc: riel@redhat.com, daniel.santos@pobox.com, aarcange@redhat.com, dwmw2@infradead.org, akpm@linux-foundation.org, linux-mm@kvack.org, linux-kernel@vger.kernel.org On Fri, Jul 27, 2012 at 1:04 PM, Peter Zijlstra wrote: > On Fri, 2012-07-20 at 05:31 -0700, Michel Lespinasse wrote: >> +static void augment_rotate(struct rb_node *rb_old, struct rb_node *rb_new) >> +{ >> + struct test_node *old = rb_entry(rb_old, struct test_node, rb); >> + struct test_node *new = rb_entry(rb_new, struct test_node, rb); >> + >> + /* Rotation doesn't change subtree's augmented value */ >> + new->augmented = old->augmented; >> + old->augmented = augment_recompute(old); >> +} > >> +static inline void augment_propagate(struct rb_node *rb) >> +{ >> + while (rb) { >> + struct test_node *node = rb_entry(rb, struct test_node, rb); >> + node->augmented = augment_recompute(node); >> + rb = rb_parent(&node->rb); >> + } >> +} > > So why do we have to introduce these two new function pointers to pass > along when they can both be trivially expressed in the old single > augment function? Its because augment_rotate() needs to be a static function that we can take the address of and pass along as a callback to the tree rebalancing functions, while augment_propagate() needs to be an inline function that gets compiled within an __rb_erase() variant for a given type of augmented rbtree. -- Michel "Walken" Lespinasse A program is never fully debugged until the last user dies. -- 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: email@kvack.org