Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754372AbbGCB0G (ORCPT ); Thu, 2 Jul 2015 21:26:06 -0400 Received: from cn.fujitsu.com ([59.151.112.132]:18582 "EHLO heian.cn.fujitsu.com" rhost-flags-OK-FAIL-OK-FAIL) by vger.kernel.org with ESMTP id S1754232AbbGCBZ5 (ORCPT ); Thu, 2 Jul 2015 21:25:57 -0400 X-IronPort-AV: E=Sophos;i="5.13,665,1427731200"; d="scan'208";a="98021008" Message-ID: <5595E4AD.8020502@cn.fujitsu.com> Date: Fri, 3 Jul 2015 09:26:05 +0800 From: Tang Chen User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:24.0) Gecko/20100101 Thunderbird/24.1.0 MIME-Version: 1.0 To: Yasuaki Ishimatsu CC: Xishi Qiu , , , , , , , , , , , , , , , , , Subject: Re: [PATCH 1/1] mem-hotplug: Handle node hole when initializing numa_meminfo. References: <1435720614-16480-1-git-send-email-tangchen@cn.fujitsu.com> <559387EF.5050701@huawei.com> <55939CF2.6080108@cn.fujitsu.com> <5595527a.0b32370a.6c7e.01ee@mx.google.com> In-Reply-To: <5595527a.0b32370a.6c7e.01ee@mx.google.com> Content-Type: text/plain; charset="ISO-8859-1"; format=flowed Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 6690 Lines: 178 On 07/02/2015 11:02 PM, Yasuaki Ishimatsu wrote: > Hi Tang, > >> On my box, if I run lscpu, the output looks like this: >> >> NUMA node0 CPU(s): 0-14,128-142 >> NUMA node1 CPU(s): 15-29,143-157 >> NUMA node2 CPU(s): >> NUMA node3 CPU(s): >> NUMA node4 CPU(s): 62-76,190-204 >> NUMA node5 CPU(s): 78-92,206-220 >> >> Node 2 and 3 are not exist, but they are online. > According your description of patch, node 4 and 5 are mistakenly Not node 4 and 5, it is node 2 and 3 which are mistakenly set online. > set to online. Why does lscpu show the above result? Well, actually not only lscpu gives the strange result, under /sys/device/system/node, interfaces for node 2 and 3 are also created. I haven't read lscpu code, so I'm not sure how lscpu handles nodes. But obviously, node 2 and 3 are set online, which is incorrect. For now, I only found that in numa_cleanup_meminfo(), memory above max_pfn is removed, but holes between nodes are not removed. I think libraries are not able to handle this problem since nodes are set online in kernel. Seeing from user space, there is no hole. Thanks. > > Thanks, > Yasuaki Ishimatsu > > On Wed, 1 Jul 2015 15:55:30 +0800 > Tang Chen wrote: > >> On 07/01/2015 02:25 PM, Xishi Qiu wrote: >>> On 2015/7/1 11:16, Tang Chen wrote: >>> >>>> When parsing SRAT, all memory ranges are added into numa_meminfo. >>>> In numa_init(), before entering numa_cleanup_meminfo(), all possible >>>> memory ranges are in numa_meminfo. And numa_cleanup_meminfo() removes >>>> all ranges over max_pfn or empty. >>>> >>>> But, this only works if the nodes are continuous. Let's have a look >>>> at the following example: >>>> >>>> We have an SRAT like this: >>>> SRAT: Node 0 PXM 0 [mem 0x00000000-0x5fffffff] >>>> SRAT: Node 0 PXM 0 [mem 0x100000000-0x1ffffffffff] >>>> SRAT: Node 1 PXM 1 [mem 0x20000000000-0x3ffffffffff] >>>> SRAT: Node 4 PXM 2 [mem 0x40000000000-0x5ffffffffff] hotplug >>>> SRAT: Node 5 PXM 3 [mem 0x60000000000-0x7ffffffffff] hotplug >>>> SRAT: Node 2 PXM 4 [mem 0x80000000000-0x9ffffffffff] hotplug >>>> SRAT: Node 3 PXM 5 [mem 0xa0000000000-0xbffffffffff] hotplug >>>> SRAT: Node 6 PXM 6 [mem 0xc0000000000-0xdffffffffff] hotplug >>>> SRAT: Node 7 PXM 7 [mem 0xe0000000000-0xfffffffffff] hotplug >>>> >>>> On boot, only node 0,1,2,3 exist. >>>> >>>> And the numa_meminfo will look like this: >>>> numa_meminfo.nr_blks = 9 >>>> 1. on node 0: [0, 60000000] >>>> 2. on node 0: [100000000, 20000000000] >>>> 3. on node 1: [20000000000, 40000000000] >>>> 4. on node 4: [40000000000, 60000000000] >>>> 5. on node 5: [60000000000, 80000000000] >>>> 6. on node 2: [80000000000, a0000000000] >>>> 7. on node 3: [a0000000000, a0800000000] >>>> 8. on node 6: [c0000000000, a0800000000] >>>> 9. on node 7: [e0000000000, a0800000000] >>>> >>>> And numa_cleanup_meminfo() will merge 1 and 2, and remove 8,9 because >>>> the end address is over max_pfn, which is a0800000000. But 4 and 5 >>>> are not removed because their end addresses are less then max_pfn. >>>> But in fact, node 4 and 5 don't exist. >>>> >>>> In a word, numa_cleanup_meminfo() is not able to handle holes between nodes. >>>> >>>> Since memory ranges in node 4 and 5 are in numa_meminfo, in numa_register_memblks(), >>>> node 4 and 5 will be mistakenly set to online. >>>> >>>> In this patch, we use memblock_overlaps_region() to check if ranges in >>>> numa_meminfo overlap with ranges in memory_block. Since memory_block contains >>>> all available memory at boot time, if they overlap, it means the ranges >>>> exist. If not, then remove them from numa_meminfo. >>>> >>> Hi Tang Chen, >>> >>> What's the impact of this problem? >>> >>> Command "numactl --hard" will show an empty node(no cpu and no memory, >>> but pgdat is created), right? >> On my box, if I run lscpu, the output looks like this: >> >> NUMA node0 CPU(s): 0-14,128-142 >> NUMA node1 CPU(s): 15-29,143-157 >> NUMA node2 CPU(s): >> NUMA node3 CPU(s): >> NUMA node4 CPU(s): 62-76,190-204 >> NUMA node5 CPU(s): 78-92,206-220 >> >> Node 2 and 3 are not exist, but they are online. >> >> Thanks. >> >>> Thanks, >>> Xishi Qiu >>> >>>> Signed-off-by: Tang Chen >>>> --- >>>> arch/x86/mm/numa.c | 6 ++++-- >>>> include/linux/memblock.h | 2 ++ >>>> mm/memblock.c | 2 +- >>>> 3 files changed, 7 insertions(+), 3 deletions(-) >>>> >>>> diff --git a/arch/x86/mm/numa.c b/arch/x86/mm/numa.c >>>> index 4053bb5..0c55cc5 100644 >>>> --- a/arch/x86/mm/numa.c >>>> +++ b/arch/x86/mm/numa.c >>>> @@ -246,8 +246,10 @@ int __init numa_cleanup_meminfo(struct numa_meminfo *mi) >>>> bi->start = max(bi->start, low); >>>> bi->end = min(bi->end, high); >>>> >>>> - /* and there's no empty block */ >>>> - if (bi->start >= bi->end) >>>> + /* and there's no empty or non-exist block */ >>>> + if (bi->start >= bi->end || >>>> + memblock_overlaps_region(&memblock.memory, >>>> + bi->start, bi->end - bi->start) == -1) >>>> numa_remove_memblk_from(i--, mi); >>>> } >>>> >>>> diff --git a/include/linux/memblock.h b/include/linux/memblock.h >>>> index 0215ffd..3bf6cc1 100644 >>>> --- a/include/linux/memblock.h >>>> +++ b/include/linux/memblock.h >>>> @@ -77,6 +77,8 @@ int memblock_remove(phys_addr_t base, phys_addr_t size); >>>> int memblock_free(phys_addr_t base, phys_addr_t size); >>>> int memblock_reserve(phys_addr_t base, phys_addr_t size); >>>> void memblock_trim_memory(phys_addr_t align); >>>> +long memblock_overlaps_region(struct memblock_type *type, >>>> + phys_addr_t base, phys_addr_t size); >>>> int memblock_mark_hotplug(phys_addr_t base, phys_addr_t size); >>>> int memblock_clear_hotplug(phys_addr_t base, phys_addr_t size); >>>> int memblock_mark_mirror(phys_addr_t base, phys_addr_t size); >>>> diff --git a/mm/memblock.c b/mm/memblock.c >>>> index 1b444c7..55b5f9f 100644 >>>> --- a/mm/memblock.c >>>> +++ b/mm/memblock.c >>>> @@ -91,7 +91,7 @@ static unsigned long __init_memblock memblock_addrs_overlap(phys_addr_t base1, p >>>> return ((base1 < (base2 + size2)) && (base2 < (base1 + size1))); >>>> } >>>> >>>> -static long __init_memblock memblock_overlaps_region(struct memblock_type *type, >>>> +long __init_memblock memblock_overlaps_region(struct memblock_type *type, >>>> phys_addr_t base, phys_addr_t size) >>>> { >>>> unsigned long i; >>> >>> . >>> > . > -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/