From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-pa0-f52.google.com (mail-pa0-f52.google.com [209.85.220.52]) by kanga.kvack.org (Postfix) with ESMTP id B55B56B0037 for ; Thu, 12 Jun 2014 17:34:22 -0400 (EDT) Received: by mail-pa0-f52.google.com with SMTP id eu11so1381171pac.11 for ; Thu, 12 Jun 2014 14:34:22 -0700 (PDT) Received: from g2t2354.austin.hp.com (g2t2354.austin.hp.com. [15.217.128.53]) by mx.google.com with ESMTPS id gr3si42794766pbb.210.2014.06.12.14.34.21 for (version=TLSv1 cipher=RC4-SHA bits=128/128); Thu, 12 Jun 2014 14:34:21 -0700 (PDT) Message-ID: <539A1CDA.5000709@hp.com> Date: Thu, 12 Jun 2014 17:34:18 -0400 From: Waiman Long MIME-Version: 1.0 Subject: Re: [PATCH] mm: Move __vma_address() to internal.h to be inlined in huge_memory.c References: <1402600540-52031-1-git-send-email-Waiman.Long@hp.com> <20140612122546.cfdebdb22bb22c0f767e30b5@linux-foundation.org> In-Reply-To: <20140612122546.cfdebdb22bb22c0f767e30b5@linux-foundation.org> Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Sender: owner-linux-mm@kvack.org List-ID: To: Andrew Morton Cc: Mel Gorman , Rik van Riel , Ingo Molnar , Peter Zijlstra , linux-kernel@vger.kernel.org, linux-mm@kvack.org, Scott J Norton On 06/12/2014 03:25 PM, Andrew Morton wrote: > On Thu, 12 Jun 2014 15:15:40 -0400 Waiman Long wrote: > >> The vma_address() function which is used to compute the virtual address >> within a VMA is used only by 2 files in the mm subsystem - rmap.c and >> huge_memory.c. This function is defined in rmap.c and is inlined by >> its callers there, but it is also declared as an external function. >> >> However, the __split_huge_page() function which calls vma_address() >> in huge_memory.c is calling it as a real function call. This is not >> as efficient as an inlined function. This patch moves the underlying >> inlined __vma_address() function to internal.h to be shared by both >> the rmap.c and huge_memory.c file. > This increases huge_memory.o's text+data_bss by 311 bytes, which makes > me suspect that it is a bad change due to its increase of kernel cache > footprint. > > Perhaps we should be noinlining __vma_address()? On my test machine, I saw an increase of 144 bytes in the text segment of huge_memory.o. The size in size is caused by an increase in the size of the __split_huge_page function. When I remove the if (unlikely(is_vm_hugetlb_page(vma))) pgoff = page->index << huge_page_order(page_hstate(page)); check, the increase in size drops down to 24 bytes. As a THP cannot be a hugetlb page, there is no point in doing this check for a THP. I will update the patch to pass in an additional argument to disable this check for __split_huge_page. -Longman -- 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