March 9, 2026 at 6:04 PM, "Mike Kelly" <[email protected] mailto:[email protected]?to=%22Mike%20Kelly%22%20%3Cmike%40weatherwax.co.uk%3E > wrote:
> > On 9 Mar 2026 20:11, Michael Kelly <[email protected]> wrote: > > > > The fundamental problem is that ext2fs, being unprivileged, cannot > > allocate memory in order to allow other memory to be released. This is > > well known, I believe, but we need to do something to reduce the > > likelihood of this scenario as there could be cases that would result in > > the system not recovering. For example, if internal memory usage was > > dominant and a large write quickly used the remaining pages (before > > unprivileged allocation is suspended) and before sync could process the > > written pages, there might be too few pages available to page out at all. > > > > I've read parts of the paper written regarding porting Hurd to L4 and the > proposal to split user memory into guaranteed and pageable portions. > > I'd be interested in prototyping a simple variant of this in gnumach whereby > a process would be guaranteed a configurable minimum of physical memory at > all times. I can imagine that there might be security and policy issues to > consider but as a first step it would be interesting to see how something > simple worked out. While you are considering alternative OSes for inspiration for the Hurd / GNU Mach... you might also take a look at x15. One of the former Hurd developers started to write a Hurd like OS from scratch. x15 I believe is the kernel. Development has stalled on that project, but we use a bit of Richard's code that he wrote from that project... https://www.sceen.net/x15/ https://hurd.ion.nu/open_issues/gnumach_memory_management.html Thanks, Joshua P.S. I really would like to document x15 on the Hurd wiki. I know Richard didn't want it documented at some point, because it wasn't quite complete enough yet. But it would fit nicely into Hurd-ng, and x15 probably flushed out a lot of nice ideas. > Might it make the resident set for rumpdisk smaller too if parts of that code > don't actually get used by Hurd? > > Mike. >
