On Tue, Sep 27, 2022 at 10:09:04AM -0400, Mikulas Patocka wrote: > > > On Wed, 21 Sep 2022, Gao Xiang wrote: > > > On Tue, Sep 20, 2022 at 01:52:38PM -0400, Mikulas Patocka wrote: > > > Hi > > > > > > Here I'm sending second version of the brd discard patches. > > > > That is quite interesting. > > > > btw, something out of topic, I once had some preliminary attempt > > to add DAX support to brd since brd works as ramdisk and brd-dax > > could have the following benefits: > > > > - DAX can be tested without PMEM devices; > > - ramdisk fses can be accessed without double page cache; > > - initrd use cases then can work well without extra page cache > > and maybe it can perform better than initramfs (without unpack > > process). > > > > I wrote some hack stuff but don't have more time working on it... > > https://git.kernel.org/pub/scm/linux/kernel/git/xiang/linux.git/log/?h=erofs/initrd-fsdax > > > > I'm not sure if others are interested in topic though. > > > > It would be helpful to get rid of all brd page->index use cases > > first. > > > > Thanks, > > Gao Xiang > > Hi > > Ramdisk DAX was there in the past, but it was removed in the kernel 4.15. Hi Mikulas! Thanks for pointing out! I didn't realize that, although I think if we really use brd driver in production, enabling DAX support for brd is much better to remove double caching so that ramdisk can become a real ramdisk for most regular files. I have no idea how other people think about ramdisk DAX, or brd is just a stuff for testing only now. If it behaves like this, sorry about the noise. Thanks, Gao Xiang > > Mikulas
