From: yulei.kernel@gmail.com
To: linux-mm@kvack.org, akpm@linux-foundation.org,
linux-fsdevel@vger.kernel.org, kvm@vger.kernel.org,
linux-kernel@vger.kernel.org, naoya.horiguchi@nec.com,
viro@zeniv.linux.org.uk, pbonzini@redhat.com
Cc: joao.m.martins@oracle.com, rdunlap@infradead.org,
sean.j.christopherson@intel.com, xiaoguangrong.eric@gmail.com,
kernellwp@gmail.com, lihaiwei.kernel@gmail.com,
Yulei Zhang <yuleixzhang@tencent.com>
Subject: [RFC V2 37/37] Add documentation for dmemfs
Date: Mon, 7 Dec 2020 19:31:30 +0800 [thread overview]
Message-ID: <6a3a71f75dad1fa440677fc1bcdc170f178be1d8.1607332046.git.yuleixzhang@tencent.com> (raw)
In-Reply-To: <cover.1607332046.git.yuleixzhang@tencent.com>
From: Yulei Zhang <yuleixzhang@tencent.com>
Introduce dmemfs.rst to document the basic usage of dmemfs.
Signed-off-by: Yulei Zhang <yuleixzhang@tencent.com>
---
Documentation/filesystems/dmemfs.rst | 58 ++++++++++++++++++++++++++++++++++++
Documentation/filesystems/index.rst | 1 +
2 files changed, 59 insertions(+)
create mode 100644 Documentation/filesystems/dmemfs.rst
diff --git a/Documentation/filesystems/dmemfs.rst b/Documentation/filesystems/dmemfs.rst
new file mode 100644
index 00000000..f13ed0c
--- /dev/null
+++ b/Documentation/filesystems/dmemfs.rst
@@ -0,0 +1,58 @@
+.. SPDX-License-Identifier: GPL-2.0
+
+=====================================
+The Direct Memory Filesystem - DMEMFS
+=====================================
+
+
+.. Table of contents
+
+ - Overview
+ - Compilation
+ - Usage
+
+Overview
+========
+
+Dmemfs (Direct Memory filesystem) is device memory or reserved
+memory based filesystem. This kind of memory is special as it
+is not managed by kernel and it is without 'struct page'. Therefore
+it can save extra memory from the host system for various usage,
+especially for guest virtual machines.
+
+It uses a kernel boot parameter ``dmem=`` to reserve the system
+memory when the host system boots up, the details can be checked
+in /Documentation/admin-guide/kernel-parameters.txt.
+
+Compilation
+===========
+
+The filesystem should be enabled by turning on the kernel configuration
+options::
+
+ CONFIG_DMEM_FS - Direct Memory filesystem support
+ CONFIG_DMEM - Allow reservation of memory for dmem
+
+
+Additionally, the following can be turned on to aid debugging::
+
+ CONFIG_DMEM_DEBUG_FS - Enable debug information for dmem
+
+Usage
+========
+
+Dmemfs supports mapping ``4K``, ``2M`` and ``1G`` size of pages to
+the userspace, for example ::
+
+ # mount -t dmemfs none -o pagesize=4K /mnt/
+
+The it can create the backing storage with 4G size ::
+
+ # truncate /mnt/dmemfs-uuid --size 4G
+
+To use as backing storage for virtual machine starts with qemu, just need
+to specify the memory-backed-file in the qemu command line like this ::
+
+ # -object memory-backend-file,id=ram-node0,mem-path=/mnt/dmemfs-uuid \
+ share=yes,size=4G,host-nodes=0,policy=preferred -numa node,nodeid=0,memdev=ram-node0
+
diff --git a/Documentation/filesystems/index.rst b/Documentation/filesystems/index.rst
index 98f59a8..23e944b 100644
--- a/Documentation/filesystems/index.rst
+++ b/Documentation/filesystems/index.rst
@@ -120,3 +120,4 @@ Documentation for filesystem implementations.
xfs-delayed-logging-design
xfs-self-describing-metadata
zonefs
+ dmemfs
--
1.8.3.1
next prev parent reply other threads:[~2020-12-07 11:35 UTC|newest]
Thread overview: 41+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-12-07 11:30 [RFC V2 00/37] Enhance memory utilization with DMEMFS yulei.kernel
2020-12-07 11:30 ` [RFC V2 01/37] fs: introduce dmemfs module yulei.kernel
2020-12-07 11:30 ` [RFC V2 02/37] mm: support direct memory reservation yulei.kernel
2020-12-07 11:30 ` [RFC V2 03/37] dmem: implement dmem memory management yulei.kernel
2020-12-07 11:30 ` [RFC V2 04/37] dmem: let pat recognize dmem yulei.kernel
2020-12-07 11:30 ` [RFC V2 05/37] dmemfs: support mmap for dmemfs yulei.kernel
2020-12-07 11:30 ` [RFC V2 06/37] dmemfs: support truncating inode down yulei.kernel
2020-12-07 11:31 ` [RFC V2 07/37] dmem: trace core functions yulei.kernel
2020-12-07 11:31 ` [RFC V2 08/37] dmem: show some statistic in debugfs yulei.kernel
2020-12-07 11:31 ` [RFC V2 09/37] dmemfs: support remote access yulei.kernel
2020-12-07 11:31 ` [RFC V2 10/37] dmemfs: introduce max_alloc_try_dpages parameter yulei.kernel
2020-12-07 11:31 ` [RFC V2 11/37] mm: export mempolicy interfaces to serve dmem allocator yulei.kernel
2020-12-07 11:31 ` [RFC V2 12/37] dmem: introduce mempolicy support yulei.kernel
2020-12-07 11:31 ` [RFC V2 13/37] mm, dmem: introduce PFN_DMEM and pfn_t_dmem yulei.kernel
2020-12-07 11:31 ` [RFC V2 14/37] mm, dmem: differentiate dmem-pmd and thp-pmd yulei.kernel
2020-12-07 11:31 ` [RFC V2 15/37] mm: add pmd_special() check for pmd_trans_huge_lock() yulei.kernel
2020-12-07 11:31 ` [RFC V2 16/37] dmemfs: introduce ->split() to dmemfs_vm_ops yulei.kernel
2020-12-07 11:31 ` [RFC V2 17/37] mm, dmemfs: support unmap_page_range() for dmemfs pmd yulei.kernel
2020-12-07 11:31 ` [RFC V2 18/37] mm: follow_pmd_mask() for dmem huge pmd yulei.kernel
2020-12-07 11:31 ` [RFC V2 19/37] mm: gup_huge_pmd() " yulei.kernel
2020-12-07 11:31 ` [RFC V2 20/37] mm: support dmem huge pmd for vmf_insert_pfn_pmd() yulei.kernel
2020-12-07 11:31 ` [RFC V2 21/37] mm: support dmem huge pmd for follow_pfn() yulei.kernel
2020-12-07 11:31 ` [RFC V2 22/37] kvm, x86: Distinguish dmemfs page from mmio page yulei.kernel
2020-12-07 11:31 ` [RFC V2 23/37] kvm, x86: introduce VM_DMEM for syscall support usage yulei.kernel
2020-12-07 11:31 ` [RFC V2 24/37] dmemfs: support hugepage for dmemfs yulei.kernel
2020-12-07 11:31 ` [RFC V2 25/37] mm, x86, dmem: fix estimation of reserved page for vaddr_get_pfn() yulei.kernel
2020-12-07 11:31 ` [RFC V2 26/37] mm, dmem: introduce pud_special() for dmem huge pud support yulei.kernel
2020-12-07 11:31 ` [RFC V2 27/37] mm: add pud_special() check to support dmem huge pud yulei.kernel
2020-12-07 11:31 ` [RFC V2 28/37] mm, dmemfs: support huge_fault() for dmemfs yulei.kernel
2020-12-07 11:31 ` [RFC V2 29/37] mm: add follow_pte_pud() to support huge pud look up yulei.kernel
2020-12-07 11:31 ` [RFC V2 30/37] dmem: introduce dmem_bitmap_alloc() and dmem_bitmap_free() yulei.kernel
2020-12-07 11:31 ` [RFC V2 31/37] dmem: introduce mce handler yulei.kernel
2020-12-07 11:31 ` [RFC V2 32/37] mm, dmemfs: register and handle the dmem mce yulei.kernel
2020-12-07 11:31 ` [RFC V2 33/37] kvm, x86: enable record_steal_time for dmem yulei.kernel
2020-12-07 11:31 ` [RFC V2 34/37] dmem: add dmem unit tests yulei.kernel
2020-12-07 11:31 ` [RFC V2 35/37] mm, dmem: introduce dregion->memmap for dmem yulei.kernel
2020-12-07 11:31 ` [RFC V2 36/37] vfio: support dmempage refcount for vfio yulei.kernel
2020-12-07 11:31 ` yulei.kernel [this message]
2020-12-24 18:27 ` [RFC V2 37/37] Add documentation for dmemfs Randy Dunlap
2020-12-07 12:02 ` [RFC V2 00/37] Enhance memory utilization with DMEMFS David Hildenbrand
2020-12-07 19:32 ` Dan Williams
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