From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755635Ab2CHVYT (ORCPT ); Thu, 8 Mar 2012 16:24:19 -0500 Received: from mail.linuxfoundation.org ([140.211.169.12]:60965 "EHLO mail.linuxfoundation.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752701Ab2CHVYQ (ORCPT ); Thu, 8 Mar 2012 16:24:16 -0500 Date: Thu, 8 Mar 2012 13:24:15 -0800 From: Andrew Morton To: Xiao Guangrong Cc: Stephen Rothwell , linux-next@vger.kernel.org, linux-kernel@vger.kernel.org, Linus Subject: Re: linux-next: manual merge of the akpm tree with Linus' tree Message-Id: <20120308132415.15359fc7.akpm@linux-foundation.org> In-Reply-To: <4F5882E6.8080202@linux.vnet.ibm.com> References: <20120308175307.b295b1013728a5666fe4571a@canb.auug.org.au> <20120307233220.5a76aa3c.akpm@linux-foundation.org> <20120308184105.5b03ec90bcddf90562181277@canb.auug.org.au> <20120307235012.847af577.akpm@linux-foundation.org> <4F5882E6.8080202@linux.vnet.ibm.com> X-Mailer: Sylpheed 3.0.2 (GTK+ 2.20.1; x86_64-pc-linux-gnu) Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Thu, 08 Mar 2012 17:59:02 +0800 Xiao Guangrong wrote: > Andrew, the patch has been reworked. > > Subject: [PATCH] hugetlb: drop prev_vma in hugetlb_get_unmapped_area_topdown() > > After the call find_vma_prev(mm, addr, &prev_vma), the following condition > is always true: > > !prev_vma || (addr >= prev_vma->vm_end) > > it can happily drop prev_vma and use find_vma() instead of find_vma_prev(). > Well OK, but the changelog is wrong - we don't call find_vma_prev() here any more. How does this look? From: Xiao Guangrong Subject: hugetlb: remove prev_vma from hugetlb_get_unmapped_area_topdown() After looking up the vma which covers or follows the cached search address, the following condition is always true: !prev_vma || (addr >= prev_vma->vm_end) so we can stop checking the previous VMA altogether. Signed-off-by: Xiao Guangrong Signed-off-by: Andrew Morton --- arch/x86/mm/hugetlbpage.c | 18 +++++------------- 1 file changed, 5 insertions(+), 13 deletions(-) diff -puN arch/x86/mm/hugetlbpage.c~hugetlb-drop-prev_vma-in-hugetlb_get_unmapped_area_topdown arch/x86/mm/hugetlbpage.c --- a/arch/x86/mm/hugetlbpage.c~hugetlb-drop-prev_vma-in-hugetlb_get_unmapped_area_topdown +++ a/arch/x86/mm/hugetlbpage.c @@ -308,7 +308,7 @@ static unsigned long hugetlb_get_unmappe { struct hstate *h = hstate_file(file); struct mm_struct *mm = current->mm; - struct vm_area_struct *vma, *prev_vma; + struct vm_area_struct *vma; unsigned long base = mm->mmap_base; unsigned long addr = addr0; unsigned long largest_hole = mm->cached_hole_size; @@ -340,22 +340,14 @@ try_again: if (!vma) return addr; - /* - * new region fits between prev_vma->vm_end and - * vma->vm_start, use it: - */ - prev_vma = vma->vm_prev; - if (addr + len <= vma->vm_start && - (!prev_vma || (addr >= prev_vma->vm_end))) { + if (addr + len <= vma->vm_start) { /* remember the address as a hint for next time */ mm->cached_hole_size = largest_hole; return (mm->free_area_cache = addr); - } else { + } else if (mm->free_area_cache == vma->vm_end) { /* pull free_area_cache down to the first hole */ - if (mm->free_area_cache == vma->vm_end) { - mm->free_area_cache = vma->vm_start; - mm->cached_hole_size = largest_hole; - } + mm->free_area_cache = vma->vm_start; + mm->cached_hole_size = largest_hole; } /* remember the largest hole we saw so far */ _