在 2024/4/24 星期三 下午 12:29, Dan Williams 写道:
Dongsheng Yang wrote:
From: Dongsheng Yang <dongsheng.yang.linux@xxxxxxxxx>
Hi all,
This patchset introduce cbd (CXL block device). It's based on linux 6.8, and available at:
https://github.com/DataTravelGuide/linux
[..]
(4) dax is not supported yet:
same with famfs, dax device is not supported here, because dax device does not support
dev_dax_iomap so far. Once dev_dax_iomap is supported, CBD can easily support DAX mode.
I am glad that famfs is mentioned here, it demonstrates you know about
it. However, unfortunately this cover letter does not offer any analysis
of *why* the Linux project should consider this additional approach to
the inter-host shared-memory enabling problem.
To be clear I am neutral at best on some of the initiatives around CXL
memory sharing vs pooling, but famfs at least jettisons block-devices
and gets closer to a purpose-built memory semantic.
So my primary question is why would Linux need both famfs and cbd? I am
sure famfs would love feedback and help vs developing competing efforts.
Hi,
Thanks for your reply, IIUC about FAMfs, the data in famfs is stored in
shared memory, and related nodes can share the data inside this file
system; whereas cbd does not store data in shared memory, it uses shared
memory as a channel for data transmission, and the actual data is stored
in the backend block device of remote nodes. In cbd, shared memory works
more like network to connect different hosts.
That is to say, in my view, FAMfs and cbd do not conflict at all; they
meet different scenario requirements. cbd simply uses shared memory to
transmit data, shared memory plays the role of a data transmission
channel, while in FAMfs, shared memory serves as a data store role.
Please correct me if I am wrong.
Thanx
.
