On Wednesday, 02/25/2004 at 12:51 EST, Mark Post <[EMAIL PROTECTED]> wrote: > I received two patches from SUSE against the 2.4.21 Linux kernel that > implement xip2fs, or Execute In Place ext2 file system. The commentary I > received was this: > "Xip2fs is a file system driver that allows you to mount an ext2-compatible > file system from a DCSS (VM Discontiguous Shared Segment). The benefit of > using xip2fs instead of mounting the file system as ext2 using the DCSS > block device driver is that xip2fs provides execute-in-place capability. > > "This means that memory-mapping a file residing on xip2fs will simply result > in the user process' page table entries pointing directly to the DCSS pages, > as opposed to reading file pages into the page cache (as a typical ext2 > mounted file system would do). > > "Since all executables and shared libraries are memory-mapped in order to > execute, running those from an xip2 mounted file system will mean that all > processes across all VM guests in the system that use these files will share > the same physical pages of memory to hold the executable code, potentially > resulting in significant overall memory savings." > > This looks like a nice way to reduce the storage footprint for Linux/390 > guests that are using a shared read-only file system in a DCSS. > > My understanding is that documentation for this new driver will be arriving > in the next week or so. When I hear anything definite, I'll send another > note to the list.
Excellent. This is what the world has been waiting for. The full power of shared memory on z/VM will be visible: A single copy of a file in memory, regardless of how many processes or virtual machines are using it. No wasted I/O operations and no wasted memory. Alan Altmark Sr. Software Engineer IBM z/VM Development
