Linux-mm Archive on lore.kernel.org
 help / color / Atom feed
From: Shakeel Butt <shakeelb@google.com>
To: SeongJae Park <sjpark@amazon.com>
Cc: Andrew Morton <akpm@linux-foundation.org>,
	SeongJae Park <sjpark@amazon.de>,
	 Jonathan.Cameron@huawei.com,
	Andrea Arcangeli <aarcange@redhat.com>,
	acme@kernel.org,  alexander.shishkin@linux.intel.com,
	amit@kernel.org, benh@kernel.crashing.org,
	 brendan.d.gregg@gmail.com,
	Brendan Higgins <brendanhiggins@google.com>,
	 Qian Cai <cai@lca.pw>, Colin Ian King <colin.king@canonical.com>,
	Jonathan Corbet <corbet@lwn.net>,
	 David Hildenbrand <david@redhat.com>,
	dwmw@amazon.com, foersleo@amazon.de,
	 Ian Rogers <irogers@google.com>,
	jolsa@redhat.com,  "Kirill A. Shutemov" <kirill@shutemov.name>,
	mark.rutland@arm.com, Mel Gorman <mgorman@suse.de>,
	 Minchan Kim <minchan@kernel.org>, Ingo Molnar <mingo@redhat.com>,
	namhyung@kernel.org,
	 "Peter Zijlstra (Intel)" <peterz@infradead.org>,
	Randy Dunlap <rdunlap@infradead.org>,
	 Rik van Riel <riel@surriel.com>,
	David Rientjes <rientjes@google.com>,
	 Steven Rostedt <rostedt@goodmis.org>,
	rppt@kernel.org, sblbir@amazon.com, shuah@kernel.org,
	 sj38.park@gmail.com, snu@amazon.de,
	Vlastimil Babka <vbabka@suse.cz>,
	 Vladimir Davydov <vdavydov.dev@gmail.com>,
	Yang Shi <yang.shi@linux.alibaba.com>,
	 Huang Ying <ying.huang@intel.com>,
	linux-damon@amazon.com,  Linux MM <linux-mm@kvack.org>,
	linux-doc@vger.kernel.org,  LKML <linux-kernel@vger.kernel.org>
Subject: Re: [PATCH v18 06/14] mm/damon: Implement callbacks for the virtual memory address spaces
Date: Thu, 16 Jul 2020 17:46:54 -0700
Message-ID: <CALvZod7Cejryb6Pkh8Pktnv68MKm=OTUKbMe1Q0BjZgK1Q1RTw@mail.gmail.com> (raw)
In-Reply-To: <20200713084144.4430-7-sjpark@amazon.com>

On Mon, Jul 13, 2020 at 1:44 AM SeongJae Park <sjpark@amazon.com> wrote:
>
> From: SeongJae Park <sjpark@amazon.de>
>
> This commit introduces a reference implementation of the address space
> specific low level primitives for the virtual address space, so that
> users of DAMON can easily monitor the data accesses on virtual address
> spaces of specific processes by simply configuring the implementation to
> be used by DAMON.
>
> The low level primitives for the fundamental access monitoring are
> defined in two parts:
> 1. Identification of the monitoring target address range for the address
> space.
> 2. Access check of specific address range in the target space.
>
> The reference implementation for the virtual address space provided by
> this commit is designed as below.
>
> PTE Accessed-bit Based Access Check
> -----------------------------------
>
> The implementation uses PTE Accessed-bit for basic access checks.  That
> is, it clears the bit for next sampling target page and checks whether
> it set again after one sampling period.  To avoid disturbing other
> Accessed bit users such as the reclamation logic, the implementation
> adjusts the ``PG_Idle`` and ``PG_Young`` appropriately, as same to the
> 'Idle Page Tracking'.
>
> VMA-based Target Address Range Construction
> -------------------------------------------
>
> Only small parts in the super-huge virtual address space of the
> processes are mapped to physical memory and accessed.  Thus, tracking
> the unmapped address regions is just wasteful.  However, because DAMON
> can deal with some level of noise using the adaptive regions adjustment
> mechanism, tracking every mapping is not strictly required but could
> even incur a high overhead in some cases.  That said, too huge unmapped
> areas inside the monitoring target should be removed to not take the
> time for the adaptive mechanism.
>
> For the reason, this implementation converts the complex mappings to
> three distinct regions that cover every mapped area of the address
> space.  Also, the two gaps between the three regions are the two biggest
> unmapped areas in the given address space.  The two biggest unmapped
> areas would be the gap between the heap and the uppermost mmap()-ed
> region, and the gap between the lowermost mmap()-ed region and the stack
> in most of the cases.  Because these gaps are exceptionally huge in
> usual address spacees, excluding these will be sufficient to make a
> reasonable trade-off.  Below shows this in detail::
>
>     <heap>
>     <BIG UNMAPPED REGION 1>
>     <uppermost mmap()-ed region>
>     (small mmap()-ed regions and munmap()-ed regions)
>     <lowermost mmap()-ed region>
>     <BIG UNMAPPED REGION 2>
>     <stack>
>
> Signed-off-by: SeongJae Park <sjpark@amazon.de>
> Reviewed-by: Leonard Foerster <foersleo@amazon.de>
[snip]
> +
> +static void damon_mkold(struct mm_struct *mm, unsigned long addr)
> +{
> +       pte_t *pte = NULL;
> +       pmd_t *pmd = NULL;
> +       spinlock_t *ptl;
> +
> +       if (follow_pte_pmd(mm, addr, NULL, &pte, &pmd, &ptl))
> +               return;
> +
> +       if (pte) {
> +               if (pte_young(*pte)) {

Any reason for skipping mmu_notifier_clear_young()? Why exclude VMs as
DAMON's target applications?

> +                       clear_page_idle(pte_page(*pte));
> +                       set_page_young(pte_page(*pte));
> +               }
> +               *pte = pte_mkold(*pte);
> +               pte_unmap_unlock(pte, ptl);
> +               return;
> +       }
> +


  reply index

Thread overview: 37+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-07-13  8:41 [PATCH v18 00/14] Introduce Data Access MONitor (DAMON) SeongJae Park
2020-07-13  8:41 ` [PATCH v18 01/14] mm/page_ext: Export lookup_page_ext() to GPL modules SeongJae Park
2020-07-13 12:08   ` Mike Rapoport
2020-07-13 12:21     ` SeongJae Park
2020-07-13 17:19       ` Mike Rapoport
2020-07-13 17:38         ` SeongJae Park
2020-07-17  9:59           ` SeongJae Park
2020-07-13  8:41 ` [PATCH v18 02/14] mm: Introduce Data Access MONitor (DAMON) SeongJae Park
2020-07-18  2:47   ` Shakeel Butt
2020-07-18 13:31     ` SeongJae Park
2020-07-29 15:31       ` Shakeel Butt
2020-07-29 17:29         ` SeongJae Park
2020-07-13  8:41 ` [PATCH v18 03/14] mm/damon: Implement region based sampling SeongJae Park
2020-07-13  8:41 ` [PATCH v18 04/14] mm/damon: Adaptively adjust regions SeongJae Park
2020-07-13  8:41 ` [PATCH v18 05/14] mm/damon: Track dynamic monitoring target regions update SeongJae Park
2020-07-13  8:41 ` [PATCH v18 06/14] mm/damon: Implement callbacks for the virtual memory address spaces SeongJae Park
2020-07-17  0:46   ` Shakeel Butt [this message]
2020-07-17  6:53     ` SeongJae Park
2020-07-17 15:17       ` Shakeel Butt
2020-07-17 16:24         ` SeongJae Park
2020-07-18  2:23           ` Shakeel Butt
2020-07-18  2:51             ` SeongJae Park
2020-07-27  7:34   ` Greg Thelen
2020-07-27  9:02     ` SeongJae Park
2020-07-28 17:42       ` Shakeel Butt
2020-07-29  6:20         ` SeongJae Park
2020-07-13  8:41 ` [PATCH v18 07/14] mm/damon: Implement access pattern recording SeongJae Park
2020-07-13  8:41 ` [PATCH v18 08/14] mm/damon: Add a tracepoint SeongJae Park
2020-07-13  8:41 ` [PATCH v18 09/14] mm/damon: Implement a debugfs interface SeongJae Park
2020-07-22 10:36   ` SeongJae Park
2020-07-13  8:41 ` [PATCH v18 10/14] tools: Introduce a minimal user-space tool for DAMON SeongJae Park
2020-07-13  8:41 ` [PATCH v18 11/14] Documentation: Add documents " SeongJae Park
2020-07-27  7:19   ` Greg Thelen
2020-07-27  7:38     ` SeongJae Park
2020-07-13  8:41 ` [PATCH v18 12/14] mm/damon: Add kunit tests SeongJae Park
2020-07-13  8:41 ` [PATCH v18 13/14] mm/damon: Add user space selftests SeongJae Park
2020-07-13  8:41 ` [PATCH v18 14/14] MAINTAINERS: Update for DAMON SeongJae Park

Reply instructions:

You may reply publicly to this message via plain-text email
using any one of the following methods:

* Save the following mbox file, import it into your mail client,
  and reply-to-all from there: mbox

  Avoid top-posting and favor interleaved quoting:
  https://en.wikipedia.org/wiki/Posting_style#Interleaved_style

* Reply using the --to, --cc, and --in-reply-to
  switches of git-send-email(1):

  git send-email \
    --in-reply-to='CALvZod7Cejryb6Pkh8Pktnv68MKm=OTUKbMe1Q0BjZgK1Q1RTw@mail.gmail.com' \
    --to=shakeelb@google.com \
    --cc=Jonathan.Cameron@huawei.com \
    --cc=aarcange@redhat.com \
    --cc=acme@kernel.org \
    --cc=akpm@linux-foundation.org \
    --cc=alexander.shishkin@linux.intel.com \
    --cc=amit@kernel.org \
    --cc=benh@kernel.crashing.org \
    --cc=brendan.d.gregg@gmail.com \
    --cc=brendanhiggins@google.com \
    --cc=cai@lca.pw \
    --cc=colin.king@canonical.com \
    --cc=corbet@lwn.net \
    --cc=david@redhat.com \
    --cc=dwmw@amazon.com \
    --cc=foersleo@amazon.de \
    --cc=irogers@google.com \
    --cc=jolsa@redhat.com \
    --cc=kirill@shutemov.name \
    --cc=linux-damon@amazon.com \
    --cc=linux-doc@vger.kernel.org \
    --cc=linux-kernel@vger.kernel.org \
    --cc=linux-mm@kvack.org \
    --cc=mark.rutland@arm.com \
    --cc=mgorman@suse.de \
    --cc=minchan@kernel.org \
    --cc=mingo@redhat.com \
    --cc=namhyung@kernel.org \
    --cc=peterz@infradead.org \
    --cc=rdunlap@infradead.org \
    --cc=riel@surriel.com \
    --cc=rientjes@google.com \
    --cc=rostedt@goodmis.org \
    --cc=rppt@kernel.org \
    --cc=sblbir@amazon.com \
    --cc=shuah@kernel.org \
    --cc=sj38.park@gmail.com \
    --cc=sjpark@amazon.com \
    --cc=sjpark@amazon.de \
    --cc=snu@amazon.de \
    --cc=vbabka@suse.cz \
    --cc=vdavydov.dev@gmail.com \
    --cc=yang.shi@linux.alibaba.com \
    --cc=ying.huang@intel.com \
    /path/to/YOUR_REPLY

  https://kernel.org/pub/software/scm/git/docs/git-send-email.html

* If your mail client supports setting the In-Reply-To header
  via mailto: links, try the mailto: link

Linux-mm Archive on lore.kernel.org

Archives are clonable:
	git clone --mirror https://lore.kernel.org/linux-mm/0 linux-mm/git/0.git

	# If you have public-inbox 1.1+ installed, you may
	# initialize and index your mirror using the following commands:
	public-inbox-init -V2 linux-mm linux-mm/ https://lore.kernel.org/linux-mm \
		linux-mm@kvack.org
	public-inbox-index linux-mm

Example config snippet for mirrors

Newsgroup available over NNTP:
	nntp://nntp.lore.kernel.org/org.kvack.linux-mm


AGPL code for this site: git clone https://public-inbox.org/public-inbox.git