From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-qg0-f51.google.com (mail-qg0-f51.google.com [209.85.192.51]) by kanga.kvack.org (Postfix) with ESMTP id 6F87D6B002B for ; Thu, 31 Dec 2015 08:05:55 -0500 (EST) Received: by mail-qg0-f51.google.com with SMTP id 6so122923596qgy.1 for ; Thu, 31 Dec 2015 05:05:55 -0800 (PST) Received: from mail-qg0-x236.google.com (mail-qg0-x236.google.com. [2607:f8b0:400d:c04::236]) by mx.google.com with ESMTPS id o97si9290749qgd.69.2015.12.31.05.05.54 for (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Thu, 31 Dec 2015 05:05:54 -0800 (PST) Received: by mail-qg0-x236.google.com with SMTP id b35so71189237qge.0 for ; Thu, 31 Dec 2015 05:05:54 -0800 (PST) MIME-Version: 1.0 In-Reply-To: <005101d14158$b50842c0$1f18c840$@samsung.com> References: <004001d14158$114be8d0$33e3ba70$@samsung.com> <005101d14158$b50842c0$1f18c840$@samsung.com> Date: Thu, 31 Dec 2015 05:05:54 -0800 Message-ID: Subject: Re: [PATCH] ARM: mm: Speed up page list initialization during boot From: Chirantan Ekbote Content-Type: text/plain; charset=UTF-8 Sender: owner-linux-mm@kvack.org List-ID: To: Jungseung Lee Cc: "linux-arm-kernel@lists.infradead.org" , linux-mm@kvack.org On Mon, Dec 28, 2015 at 2:15 AM, Jungseung Lee wrote: > Hi, > >>During boot, we populate the page lists by using the page freeing >>mechanism on every individual page. Unfortunately, this is very >>inefficient because the memory manager spends a lot of time coalescing >>pairs of adjacent free pages into bigger blocks. >> >>Rather than adding a single order 0 page at a time, we can take >>advantage of the fact that we know that all the pages are available and >>free up big blocks of pages at a time instead. >> >>Signed-off-by: Chirantan Ekbote >>--- >> arch/arm/mm/init.c | 19 +++++++++++++++++-- include/linux/gfp.h | 1 >>+ >> mm/internal.h | 1 - >> 3 files changed, 18 insertions(+), 3 deletions(-) >> >>diff --git a/arch/arm/mm/init.c b/arch/arm/mm/init.c index >>97c293e..c7fc2d8 100644 >>--- a/arch/arm/mm/init.c >>+++ b/arch/arm/mm/init.c >>@@ -22,6 +22,7 @@ >> #include >> #include >> #include >>+#include >> >> #include >> #include >>@@ -469,8 +470,22 @@ static void __init free_unused_memmap(struct >>meminfo > *mi) >> #ifdef CONFIG_HIGHMEM >> static inline void free_area_high(unsigned long pfn, unsigned long >>end) { >>- for (; pfn < end; pfn++) >>- free_highmem_page(pfn_to_page(pfn)); >>+ while (pfn < end) { >>+ struct page *page = pfn_to_page(pfn); >>+ unsigned long order = min(__ffs(pfn), MAX_ORDER - 1); >>+ unsigned long nr_pages = 1 << order; >>+ unsigned long rem = end - pfn; >>+ >>+ if (nr_pages > rem) { >>+ order = __fls(rem); >>+ nr_pages = 1 << order; >>+ } >>+ >>+ __free_pages_bootmem(page, order); >>+ totalram_pages += nr_pages; >>+ totalhigh_pages += nr_pages; >>+ pfn += nr_pages; >>+ } >> } >> #endif >> >>diff --git a/include/linux/gfp.h b/include/linux/gfp.h index >>39b81dc..a63d666 100644 >>--- a/include/linux/gfp.h >>+++ b/include/linux/gfp.h >>@@ -367,6 +367,7 @@ void *alloc_pages_exact_nid(int nid, size_t size, >>gfp_t > gfp_mask); >> #define __get_dma_pages(gfp_mask, order) \ >> __get_free_pages((gfp_mask) | GFP_DMA, (order)) >> >>+extern void __free_pages_bootmem(struct page *page, unsigned int >>+order); >> extern void __free_pages(struct page *page, unsigned int order); >>extern void free_pages(unsigned long addr, unsigned int order); extern >>void free_hot_cold_page(struct page *page, int cold); diff --git >>a/mm/internal.h b/mm/internal.h index 29e1e76..d2b8738 100644 >>--- a/mm/internal.h >>+++ b/mm/internal.h >>@@ -93,7 +93,6 @@ extern pmd_t *mm_find_pmd(struct mm_struct *mm, >>unsigned > long address); >> /* >> * in mm/page_alloc.c >> */ >>-extern void __free_pages_bootmem(struct page *page, unsigned int >>order); extern void prep_compound_page(struct page *page, unsigned >>long order); #ifdef CONFIG_MEMORY_FAILURE extern bool >>is_free_buddy_page(struct page *page); >>-- >>1.9.1.423.g4596e3a > > This patch really could save boot time. > Is there any reason this patch is not merged to mainline kernel? > Well it was ignored when I originally posted it so I assumed mainline developers weren't really interested. I can re-spin and send a new version if there's interest in getting it merged now. > Best Regards, > Jungseung Lee > -- 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