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 [thread overview]
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;
> + }
> +
next prev parent reply other threads:[~2020-07-17 0:47 UTC|newest]
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
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