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From: Muchun Song <muchun.song@linux.dev>
To: Yilei Zheng <trilith.zheng@gmail.com>
Cc: Muchun Song <songmuchun@bytedance.com>,
	Andrew Morton <akpm@linux-foundation.org>,
	Dan Williams <djbw@kernel.org>,
	David Hildenbrand <david@kernel.org>,
	Oscar Salvador <osalvador@suse.de>,
	Pankaj Gupta <pankaj.gupta@amd.com>,
	linux-mm@kvack.org, nvdimm@lists.linux.dev,
	linux-kernel@vger.kernel.org, linux-fsdevel@vger.kernel.org,
	linux-cxl@vger.kernel.org,
	Vishal Verma <vishal.l.verma@intel.com>,
	Dave Jiang <dave.jiang@intel.com>,
	Alison Schofield <alison.schofield@intel.com>,
	Mike Rapoport <rppt@kernel.org>, Ira Weiny <iweiny@kernel.org>,
	Jan Kara <jack@suse.cz>, Matthew Wilcox <willy@infradead.org>,
	Lorenzo Stoakes <ljs@kernel.org>,
	Vlastimil Babka <vbabka@kernel.org>,
	Michal Hocko <mhocko@suse.com>, Qi Zheng <qi.zheng@linux.dev>
Subject: Re: [PATCH 3/4] mm: add shared read-only vmemmap support for FS-DAX
Date: Thu, 29 Oct 2026 15:31:20 +0800	[thread overview]
Message-ID: <F2127C8C-BBA5-4AC5-8F12-577346FB7F31@linux.dev> (raw)
In-Reply-To: <20261029071206.19059-1-trilith.zheng@gmail.com>



> On Oct 29, 2026, at 15:12, Yilei Zheng <trilith.zheng@gmail.com> wrote:
> 
> I forgot to mention the tool execution case in my last mail. Those
> microVMs start, run a small task, and exit. DAX is there to save
> memory, but the vmemmap is allocated for the whole image. A 2 GiB
> image pays 32 MiB of vmemmap even if a microVM only reads a few MB, so
> for those microVMs the DAX setup can use more memory than the same
> image on virtio-blk. That is also a case this series fixes for us.

Thanks for sharing. I think in this scenario it also saves boot time.
I'm not sure how significant that is, though, since the number of
vmemmap pages isn't large enough to be noticeable.

Thanks.

  reply	other threads:[~2026-10-29  7:31 UTC|newest]

Thread overview: 24+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2026-09-03 12:21 [PATCH 0/4] mm: Reduce struct page overhead for FS-DAX pmem Muchun Song
2026-09-03 12:21 ` [PATCH 1/4] mm: generalize vmemmap remap architecture support Muchun Song
2026-09-21 12:25   ` Oscar Salvador (SUSE)
2026-10-29  7:03   ` Mike Rapoport
2026-09-03 12:21 ` [PATCH 2/4] nvdimm/pmem: avoid HWPoison flag updates for clean pages Muchun Song
2026-09-03 12:41   ` sashiko-bot
2026-09-21  7:33   ` Gupta, Pankaj
2026-09-21 12:53   ` Oscar Salvador (SUSE)
2026-09-22  2:33     ` Muchun Song
2026-09-03 12:21 ` [PATCH 3/4] mm: add shared read-only vmemmap support for FS-DAX Muchun Song
2026-09-21  6:42   ` Gupta, Pankaj
2026-09-21  9:33     ` Muchun Song
2026-09-21 11:05       ` Gupta, Pankaj
2026-09-21 13:09   ` Oscar Salvador (SUSE)
2026-09-22  3:17     ` Muchun Song
2026-10-27  6:57   ` Yilei Zheng
2026-10-28  9:15     ` Muchun Song
2026-10-29  3:05       ` Yilei Zheng
2026-10-29  5:35         ` Muchun Song
2026-10-29  6:45           ` Yilei Zheng
2026-10-29  7:12           ` Yilei Zheng
2026-10-29  7:31             ` Muchun Song [this message]
     [not found] ` <20260903122128.12264-5-songmuchun@bytedance.com>
2026-09-03 12:53   ` [PATCH 4/4] fsdax: materialize pmem vmemmap metadata on faults sashiko-bot
2026-09-05  3:26     ` Muchun Song

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