From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id C0E65C19F2D for ; Thu, 4 Aug 2022 08:04:29 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S239417AbiHDIE2 (ORCPT ); Thu, 4 Aug 2022 04:04:28 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:50910 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S239396AbiHDIEY (ORCPT ); Thu, 4 Aug 2022 04:04:24 -0400 Received: from out30-42.freemail.mail.aliyun.com (out30-42.freemail.mail.aliyun.com [115.124.30.42]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 29F7461DB6 for ; Thu, 4 Aug 2022 01:04:21 -0700 (PDT) X-Alimail-AntiSpam: AC=PASS;BC=-1|-1;BR=01201311R121e4;CH=green;DM=||false|;DS=||;FP=0|-1|-1|-1|0|-1|-1|-1;HT=ay29a033018046059;MF=xhao@linux.alibaba.com;NM=1;PH=DS;RN=7;SR=0;TI=SMTPD_---0VLLXZiJ_1659600257; Received: from 30.240.99.20(mailfrom:xhao@linux.alibaba.com fp:SMTPD_---0VLLXZiJ_1659600257) by smtp.aliyun-inc.com; Thu, 04 Aug 2022 16:04:18 +0800 Message-ID: Date: Thu, 4 Aug 2022 16:04:17 +0800 MIME-Version: 1.0 User-Agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10.15; rv:102.0) Gecko/20100101 Thunderbird/102.0.3 Subject: Re: [RFC PATCH V4 1/1] mm: add last level page table numa info to /proc/pid/numa_pgtable To: David Hildenbrand , willy@infradead.org Cc: akpm@linux-foundation.org, adobriyan@gmail.com, keescook@chromium.org, linux-kernel@vger.kernel.org, linux-mm@kvack.org References: <20220801121727.76186-1-xhao@linux.alibaba.com> <20220801121727.76186-2-xhao@linux.alibaba.com> <0c1f9e76-9b1d-7069-bb09-c18e4f19f0c4@redhat.com> From: haoxin In-Reply-To: <0c1f9e76-9b1d-7069-bb09-c18e4f19f0c4@redhat.com> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 在 2022/8/1 下午9:28, David Hildenbrand 写道: > On 01.08.22 14:17, Xin Hao wrote: >> In many data center servers, the shared memory architectures is >> Non-Uniform Memory Access (NUMA), remote numa node data access >> often brings a high latency problem, but what we are easy to ignore >> is that the page table remote numa access, It can also leads to a >> performance degradation. > Let me try rewriting: > > " > Many data center servers employ Non-Uniform Memory Access (NUMA) > architectures. Remote numa memory access results in high latency. While > memory placement is one issue, sub-optimal page table placement can also > result in surprise performance degradation. > " Thanks,  it reads more clearly. >> So there add a new interface in /proc, This will help developers to >> get more info about performance issues if they are caused by cross-NUMA. > > Why do we only care about "last level page table", why not about the others? > > IMHO, we could emit something like "0, 1, 3, 0" instead for a given user > space address, showing the NUMA node the page table belongs to from > highest to lowest page table level. I have planned to implement the PTE page table in this version first,  and then support other page tables in the next patch later. > >> Reported-by: kernel test robot > The kernel test robot reported that we need "/proc/pid/numa_pgtable" ?! :) > > Just drop that unless it's a follow-up fix. Get it. > >> Signed-off-by: Xin Hao >> --- >> fs/proc/base.c | 2 ++ >> fs/proc/internal.h | 1 + >> fs/proc/task_mmu.c | 87 ++++++++++++++++++++++++++++++++++++++++++++++ >> 3 files changed, 90 insertions(+) >> >> diff --git a/fs/proc/base.c b/fs/proc/base.c >> index 8dfa36a99c74..487e82dd3275 100644 >> --- a/fs/proc/base.c >> +++ b/fs/proc/base.c >> @@ -3224,6 +3224,7 @@ static const struct pid_entry tgid_base_stuff[] = { >> REG("maps", S_IRUGO, proc_pid_maps_operations), >> #ifdef CONFIG_NUMA >> REG("numa_maps", S_IRUGO, proc_pid_numa_maps_operations), >> + REG("numa_pgtable", S_IRUGO, proc_pid_numa_pgtable_operations), >> #endif >> REG("mem", S_IRUSR|S_IWUSR, proc_mem_operations), >> LNK("cwd", proc_cwd_link), >> @@ -3571,6 +3572,7 @@ static const struct pid_entry tid_base_stuff[] = { >> #endif >> #ifdef CONFIG_NUMA >> REG("numa_maps", S_IRUGO, proc_pid_numa_maps_operations), >> + REG("numa_pgtable", S_IRUGO, proc_pid_numa_pgtable_operations), >> #endif >> REG("mem", S_IRUSR|S_IWUSR, proc_mem_operations), >> LNK("cwd", proc_cwd_link), >> diff --git a/fs/proc/internal.h b/fs/proc/internal.h >> index 06a80f78433d..e7ed9ef097b6 100644 >> --- a/fs/proc/internal.h >> +++ b/fs/proc/internal.h >> @@ -296,6 +296,7 @@ struct mm_struct *proc_mem_open(struct inode *inode, unsigned int mode); >> >> extern const struct file_operations proc_pid_maps_operations; >> extern const struct file_operations proc_pid_numa_maps_operations; >> +extern const struct file_operations proc_pid_numa_pgtable_operations; >> extern const struct file_operations proc_pid_smaps_operations; >> extern const struct file_operations proc_pid_smaps_rollup_operations; >> extern const struct file_operations proc_clear_refs_operations; >> diff --git a/fs/proc/task_mmu.c b/fs/proc/task_mmu.c >> index 2d04e3470d4c..77b7a49757f5 100644 >> --- a/fs/proc/task_mmu.c >> +++ b/fs/proc/task_mmu.c >> @@ -1999,4 +1999,91 @@ const struct file_operations proc_pid_numa_maps_operations = { >> .release = proc_map_release, >> }; >> >> +struct pgtable_numa_private { >> + struct proc_maps_private proc_maps; >> + unsigned long node[MAX_NUMNODES]; >> +}; >> + >> +static int gather_pgtable_numa_stats(pmd_t *pmd, unsigned long addr, >> + unsigned long end, struct mm_walk *walk) >> +{ >> + struct pgtable_numa_private *priv = walk->private; >> + struct page *page; >> + int nid; >> + >> + if (pmd_huge(*pmd)) { >> + page = virt_to_page(pmd); >> + } else { >> + page = pmd_page(*pmd); >> + } >> + >> + nid = page_to_nid(page); >> + priv->node[nid]++; >> + >> + return 0; >> +} >> + >> +static const struct mm_walk_ops show_numa_pgtable_ops = { >> + .pmd_entry = gather_pgtable_numa_stats, >> +}; >> + >> +/* >> + * Display the page talbe allocated per node via /proc. > s/talbe/table/ > > but the comment somehow doesn't make sense. We don't display a page table. > >> + */ >> +static int show_numa_pgtable(struct seq_file *m, void *v) >> +{ >> + struct pgtable_numa_private *numa_priv = m->private; >> + struct vm_area_struct *vma = v; >> + struct mm_struct *mm = vma->vm_mm; >> + struct file *file = vma->vm_file; >> + int nid; >> + >> + if (!mm) >> + return 0; >> + >> + memset(numa_priv->node, 0, sizeof(numa_priv->node)); >> + >> + seq_printf(m, "%08lx ", vma->vm_start); >> + >> + if (file) { >> + seq_puts(m, " file="); >> + seq_file_path(m, file, "\n\t= "); >> + } else if (vma->vm_start <= mm->brk && vma->vm_end >= mm->start_brk) { >> + seq_puts(m, " heap"); >> + } else if (is_stack(vma)) { >> + seq_puts(m, " stack"); >> + } >> + >> + /* mmap_lock is held by m_start */ >> + walk_page_vma(vma, &show_numa_pgtable_ops, numa_priv); >> + >> + for_each_node_state(nid, N_MEMORY) { >> + if (numa_priv->node[nid]) >> + seq_printf(m, " N%d=%lu", nid, numa_priv->node[nid]); >> + } >> + seq_putc(m, '\n'); >> + >> + return 0; >> +} >> + >> +static const struct seq_operations proc_pid_numa_pgtable_op = { >> + .start = m_start, >> + .next = m_next, >> + .stop = m_stop, >> + .show = show_numa_pgtable, >> +}; >> + >> +static int pid_numa_pgtable_open(struct inode *inode, struct file *file) >> +{ >> + return proc_maps_open(inode, file, &proc_pid_numa_pgtable_op, >> + sizeof(struct pgtable_numa_private)); >> +} >> + >> +const struct file_operations proc_pid_numa_pgtable_operations = { >> + .open = pid_numa_pgtable_open, >> + .read = seq_read, >> + .llseek = seq_lseek, >> + .release = proc_map_release, >> +}; >> + >> #endif /* CONFIG_NUMA */ >> -- >> 2.31.0 >> >