From: Randy Dunlap <rdunlap@infradead.org>
To: yulei.kernel@gmail.com, akpm@linux-foundation.org,
naoya.horiguchi@nec.com, viro@zeniv.linux.org.uk,
pbonzini@redhat.com
Cc: linux-fsdevel@vger.kernel.org, kvm@vger.kernel.org,
linux-kernel@vger.kernel.org, xiaoguangrong.eric@gmail.com,
kernellwp@gmail.com, lihaiwei.kernel@gmail.com,
Yulei Zhang <yuleixzhang@tencent.com>
Subject: Re: [PATCH 35/35] Add documentation for dmemfs
Date: Thu, 8 Oct 2020 18:26:35 -0700 [thread overview]
Message-ID: <7f4f18b4-130e-ce51-3149-8a1ad348dc2a@infradead.org> (raw)
In-Reply-To: <4d1bc80e93134fb0f5691db5c4bb8bcbc1e716dd.1602093760.git.yuleixzhang@tencent.com>
On 10/8/20 12:54 AM, yulei.kernel@gmail.com wrote:
> From: Yulei Zhang <yuleixzhang@tencent.com>
>
> Introduce dmemfs.rst to document the basic usage of dmemfs.
>
Please add dmemfs as an entry in Documentation/filesystems/index.rst also.
> Signed-off-by: Yulei Zhang <yuleixzhang@tencent.com>
> ---
> Documentation/filesystems/dmemfs.rst | 59 ++++++++++++++++++++++++++++
> 1 file 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 000000000000..cbb4cc1ed31d
> --- /dev/null
> +++ b/Documentation/filesystems/dmemfs.rst
> @@ -0,0 +1,57 @@
> +.. 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,
usages,
> +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
up. The details
> +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
Hm, is there a good reason for having both of these options?
Is one of them usable without the other one?
If not, there should only be one Kconfig option for DMEMFS.
> +
> +
> +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 ::
Then
> +
> + # 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
>
--
~Randy
next prev parent reply other threads:[~2020-10-09 1:27 UTC|newest]
Thread overview: 61+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-10-08 7:53 [PATCH 00/35] Enhance memory utilization with DMEMFS yulei.kernel
2020-10-08 7:53 ` [PATCH 01/35] fs: introduce dmemfs module yulei.kernel
2020-11-10 20:04 ` Al Viro
2020-11-11 8:53 ` yulei zhang
2020-11-11 23:09 ` Al Viro
2020-11-12 10:03 ` yulei zhang
2020-10-08 7:53 ` [PATCH 02/35] mm: support direct memory reservation yulei.kernel
2020-10-08 20:27 ` Randy Dunlap
2020-10-08 20:34 ` Randy Dunlap
2020-10-08 7:53 ` [PATCH 03/35] dmem: implement dmem memory management yulei.kernel
2020-10-08 7:53 ` [PATCH 04/35] dmem: let pat recognize dmem yulei.kernel
2020-10-13 7:27 ` Paolo Bonzini
2020-10-13 9:53 ` yulei zhang
2020-10-08 7:53 ` [PATCH 05/35] dmemfs: support mmap yulei.kernel
2020-10-08 7:53 ` [PATCH 06/35] dmemfs: support truncating inode down yulei.kernel
2020-10-08 7:53 ` [PATCH 07/35] dmem: trace core functions yulei.kernel
2020-10-08 7:53 ` [PATCH 08/35] dmem: show some statistic in debugfs yulei.kernel
2020-10-08 20:23 ` Randy Dunlap
2020-10-09 11:49 ` yulei zhang
2020-10-08 7:53 ` [PATCH 09/35] dmemfs: support remote access yulei.kernel
2020-10-08 7:54 ` [PATCH 10/35] dmemfs: introduce max_alloc_try_dpages parameter yulei.kernel
2020-10-08 7:54 ` [PATCH 11/35] mm: export mempolicy interfaces to serve dmem allocator yulei.kernel
2020-10-08 7:54 ` [PATCH 12/35] dmem: introduce mempolicy support yulei.kernel
2020-10-08 7:54 ` [PATCH 13/35] mm, dmem: introduce PFN_DMEM and pfn_t_dmem yulei.kernel
2020-10-08 7:54 ` [PATCH 14/35] mm, dmem: dmem-pmd vs thp-pmd yulei.kernel
2020-10-08 7:54 ` [PATCH 15/35] mm: add pmd_special() check for pmd_trans_huge_lock() yulei.kernel
2020-10-08 7:54 ` [PATCH 16/35] dmemfs: introduce ->split() to dmemfs_vm_ops yulei.kernel
2020-10-08 7:54 ` [PATCH 17/35] mm, dmemfs: support unmap_page_range() for dmemfs pmd yulei.kernel
2020-10-08 7:54 ` [PATCH 18/35] mm: follow_pmd_mask() for dmem huge pmd yulei.kernel
2020-10-08 7:54 ` [PATCH 19/35] mm: gup_huge_pmd() " yulei.kernel
2020-10-08 7:54 ` [PATCH 20/35] mm: support dmem huge pmd for vmf_insert_pfn_pmd() yulei.kernel
2020-10-08 7:54 ` [PATCH 21/35] mm: support dmem huge pmd for follow_pfn() yulei.kernel
2020-10-08 7:54 ` [PATCH 22/35] kvm, x86: Distinguish dmemfs page from mmio page yulei.kernel
2020-10-09 0:58 ` Sean Christopherson
2020-10-09 10:28 ` Joao Martins
2020-10-09 11:42 ` yulei zhang
2020-10-08 7:54 ` [PATCH 23/35] kvm, x86: introduce VM_DMEM yulei.kernel
2020-10-08 7:54 ` [PATCH 24/35] dmemfs: support hugepage for dmemfs yulei.kernel
2020-10-08 7:54 ` [PATCH 25/35] mm, x86, dmem: fix estimation of reserved page for vaddr_get_pfn() yulei.kernel
2020-10-08 7:54 ` [PATCH 26/35] mm, dmem: introduce pud_special() yulei.kernel
2020-10-08 7:54 ` [PATCH 27/35] mm: add pud_special() to support dmem huge pud yulei.kernel
2020-10-08 7:54 ` [PATCH 28/35] mm, dmemfs: support huge_fault() for dmemfs yulei.kernel
2020-10-08 7:54 ` [PATCH 29/35] mm: add follow_pte_pud() yulei.kernel
2020-10-08 7:54 ` [PATCH 30/35] dmem: introduce dmem_bitmap_alloc() and dmem_bitmap_free() yulei.kernel
2020-10-08 7:54 ` [PATCH 31/35] dmem: introduce mce handler yulei.kernel
2020-10-08 7:54 ` [PATCH 32/35] mm, dmemfs: register and handle the dmem mce yulei.kernel
2020-10-08 7:54 ` [PATCH 33/35] kvm, x86: temporary disable record_steal_time for dmem yulei.kernel
2020-10-08 7:54 ` [PATCH 34/35] dmem: add dmem unit tests yulei.kernel
2020-10-08 7:54 ` [PATCH 35/35] Add documentation for dmemfs yulei.kernel
2020-10-09 1:26 ` Randy Dunlap [this message]
2020-10-08 19:01 ` [PATCH 00/35] Enhance memory utilization with DMEMFS Joao Martins
2020-10-09 11:39 ` yulei zhang
2020-10-09 11:53 ` Joao Martins
2020-10-10 8:15 ` yulei zhang
2020-10-12 10:59 ` Joao Martins
2020-10-14 22:25 ` Dan Williams
2020-10-19 13:37 ` Paolo Bonzini
2020-10-19 19:03 ` Joao Martins
2020-10-20 15:22 ` yulei zhang
2020-10-12 11:57 ` Zengtao (B)
2020-10-13 2:45 ` yulei zhang
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