From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-lf0-f70.google.com (mail-lf0-f70.google.com [209.85.215.70]) by kanga.kvack.org (Postfix) with ESMTP id 49735828E1 for ; Fri, 5 Aug 2016 11:32:00 -0400 (EDT) Received: by mail-lf0-f70.google.com with SMTP id k135so155254584lfb.2 for ; Fri, 05 Aug 2016 08:32:00 -0700 (PDT) Received: from mx2.suse.de (mx2.suse.de. [195.135.220.15]) by mx.google.com with ESMTPS id y12si17109384wjw.183.2016.08.04.23.45.06 for (version=TLS1 cipher=AES128-SHA bits=128/128); Thu, 04 Aug 2016 23:45:06 -0700 (PDT) Subject: Re: [PATCH V2 1/2] mm/page_alloc: Replace set_dma_reserve to set_memory_reserve References: <1470330729-6273-1-git-send-email-srikar@linux.vnet.ibm.com> From: Vlastimil Babka Message-ID: <09d5b30e-5956-bf64-5f4c-ea5425d7f7a5@suse.cz> Date: Fri, 5 Aug 2016 08:45:03 +0200 MIME-Version: 1.0 In-Reply-To: <1470330729-6273-1-git-send-email-srikar@linux.vnet.ibm.com> Content-Type: text/plain; charset=utf-8; format=flowed Content-Transfer-Encoding: 7bit Sender: owner-linux-mm@kvack.org List-ID: To: Srikar Dronamraju , linux-mm@kvack.org, Mel Gorman , Michal Hocko , Andrew Morton , Michael Ellerman , linuxppc-dev@lists.ozlabs.org, Mahesh Salgaonkar , Hari Bathini Cc: Dave Hansen , Balbir Singh On 08/04/2016 07:12 PM, Srikar Dronamraju wrote: > Expand the scope of the existing dma_reserve to accommodate other memory > reserves too. Accordingly rename variable dma_reserve to > nr_memory_reserve. > > set_memory_reserve also takes a new parameter that helps to identify if > the current value needs to be incremented. > > Suggested-by: Mel Gorman > Signed-off-by: Srikar Dronamraju > --- > arch/x86/kernel/e820.c | 2 +- > include/linux/mm.h | 2 +- > mm/page_alloc.c | 20 ++++++++++++-------- > 3 files changed, 14 insertions(+), 10 deletions(-) > > diff --git a/arch/x86/kernel/e820.c b/arch/x86/kernel/e820.c > index 621b501..d935983 100644 > --- a/arch/x86/kernel/e820.c > +++ b/arch/x86/kernel/e820.c > @@ -1188,6 +1188,6 @@ void __init memblock_find_dma_reserve(void) > nr_free_pages += end_pfn - start_pfn; > } > > - set_dma_reserve(nr_pages - nr_free_pages); > + set_memory_reserve(nr_pages - nr_free_pages, false); > #endif > } > diff --git a/include/linux/mm.h b/include/linux/mm.h > index 8f468e0..c884ffb 100644 > --- a/include/linux/mm.h > +++ b/include/linux/mm.h > @@ -1886,7 +1886,7 @@ extern int __meminit __early_pfn_to_nid(unsigned long pfn, > struct mminit_pfnnid_cache *state); > #endif > > -extern void set_dma_reserve(unsigned long new_dma_reserve); > +extern void set_memory_reserve(unsigned long nr_reserve, bool inc); > extern void memmap_init_zone(unsigned long, int, unsigned long, > unsigned long, enum memmap_context); > extern void setup_per_zone_wmarks(void); > diff --git a/mm/page_alloc.c b/mm/page_alloc.c > index c1069ef..a154c2f 100644 > --- a/mm/page_alloc.c > +++ b/mm/page_alloc.c > @@ -253,7 +253,7 @@ int watermark_scale_factor = 10; > > static unsigned long __meminitdata nr_kernel_pages; > static unsigned long __meminitdata nr_all_pages; > -static unsigned long __meminitdata dma_reserve; > +static unsigned long __meminitdata nr_memory_reserve; > > #ifdef CONFIG_HAVE_MEMBLOCK_NODE_MAP > static unsigned long __meminitdata arch_zone_lowest_possible_pfn[MAX_NR_ZONES]; > @@ -5493,10 +5493,10 @@ static void __paginginit free_area_init_core(struct pglist_data *pgdat) > } > > /* Account for reserved pages */ > - if (j == 0 && freesize > dma_reserve) { > - freesize -= dma_reserve; > + if (j == 0 && freesize > nr_memory_reserve) { Will this really work (together with patch 2) as intended? This j == 0 means that we are doing this only for the first zone, which is ZONE_DMA (or ZONE_DMA32) on node 0 on many systems. I.e. I don't think it's really true that "dma_reserve has nothing to do with DMA or ZONE_DMA". This zone will have limited amount of memory, so the "freesize > nr_memory_reserve" will easily be false once you set this to many gigabytes, so in fact nothing will get subtracted. On the other hand if the kernel has both CONFIG_ZONE_DMA and CONFIG_ZONE_DMA32 disabled, then j == 0 will be true for ZONE_NORMAL. This zone might be present on multiple nodes (unless they are configured as movable) and then the value intended to be global will be subtracted from several nodes. I don't know what's the exact ppc64 situation here, perhaps there are indeed no DMA/DMA32 zones, and the fadump kernel only uses one node, so it works in the end, but it doesn't seem much robust to me? > + freesize -= nr_memory_reserve; > printk(KERN_DEBUG " %s zone: %lu pages reserved\n", > - zone_names[0], dma_reserve); > + zone_names[0], nr_memory_reserve); > } > > if (!is_highmem_idx(j)) > @@ -6186,8 +6186,9 @@ void __init mem_init_print_info(const char *str) > } > > /** > - * set_dma_reserve - set the specified number of pages reserved in the first zone > - * @new_dma_reserve: The number of pages to mark reserved > + * set_memory_reserve - set number of pages reserved in the first zone > + * @nr_reserve: The number of pages to mark reserved > + * @inc: true increment to existing value; false set new value. > * > * The per-cpu batchsize and zone watermarks are determined by managed_pages. > * In the DMA zone, a significant percentage may be consumed by kernel image > @@ -6196,9 +6197,12 @@ void __init mem_init_print_info(const char *str) > * first zone (e.g., ZONE_DMA). The effect will be lower watermarks and > * smaller per-cpu batchsize. > */ > -void __init set_dma_reserve(unsigned long new_dma_reserve) > +void __init set_memory_reserve(unsigned long nr_reserve, bool inc) > { > - dma_reserve = new_dma_reserve; > + if (inc) > + nr_memory_reserve += nr_reserve; > + else > + nr_memory_reserve = nr_reserve; > } > > void __init free_area_init(unsigned long *zones_size) > -- 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