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I'm surprised that none of the efforts listed seem to target hypervisors like Xen or KVM. A few weeks ago, Azul's VM was on HN, and its GC benefits from tight

by limmeau 16y ago

I'm surprised that none of the efforts listed seem to target hypervisors like Xen or KVM. A few weeks ago, Azul's VM was on HN, and its GC benefits from tight integration with the virtual memory system.

procrastitron 16y ago
That page doesn't seem to have been updated in the several years since I first came across it. As such, any efforts targeting Xen or KVM wouldn't have existed at the time the list was put together.
chalst 16y ago
That list is fairly old: I remember it from way back. I'm pretty sure most of it predates KVM by a long stretch.
sedachv 16y ago
You can get Azul's Linux patches here: http://www.managedruntime.org/ http://www.managedruntime.org/ From what I understand, the main win is that they use nested page tables to let the JVMs handle page faults directly, which is how they implement high-performance read barriers. I don't know a lot about garbage collection, but read barriers seem to be the essential piece for implementing real-time (which really should be called "non-blocking") GC. There's a good discussion on LtU about this: http://lambda-the-ultimate.org/node/4165 http://lambda-the-ultimate.org/node/4165 [edit] I should mention how this relates to Lisp operating systems: if you replace the virtual memory system with a garbage collector (ie push the GC into the kernel), you can get the same effect but without needing nested page tables/VT-x/RVI, even for user-space processes. It should also be more efficient and waste less memory on fragmentation than going through a dumb VM.
nwmcsween 16y ago
This is by effectively bypassing Linux. The same can be said for any operating system that allows applications to do what they want to a greater degree - look at http://pdos.csail.mit.edu/exo http://pdos.csail.mit.edu/exo http://en.wikipedia.org/wiki/Midori_(operating_system) http://en.wikipedia.org/wiki/Midori_(operating_system) Although I don't know much about midori

by limmeau 16y ago

procrastitron 16y ago

That page doesn't seem to have been updated in the several years since I first came across it. As such, any efforts targeting Xen or KVM wouldn't have existed at the time the list was put together.

chalst 16y ago

That list is fairly old: I remember it from way back. I'm pretty sure most of it predates KVM by a long stretch.

sedachv 16y ago

You can get Azul's Linux patches here: http://www.managedruntime.org/ http://www.managedruntime.org/ From what I understand, the main win is that they use nested page tables to let the JVMs handle page faults directly, which is how they implement high-performance read barriers. I don't know a lot about garbage collection, but read barriers seem to be the essential piece for implementing real-time (which really should be called "non-blocking") GC. There's a good discussion on LtU about this: http://lambda-the-ultimate.org/node/4165 http://lambda-the-ultimate.org/node/4165 [edit] I should mention how this relates to Lisp operating systems: if you replace the virtual memory system with a garbage collector (ie push the GC into the kernel), you can get the same effect but without needing nested page tables/VT-x/RVI, even for user-space processes. It should also be more efficient and waste less memory on fragmentation than going through a dumb VM.

nwmcsween 16y ago

This is by effectively bypassing Linux. The same can be said for any operating system that allows applications to do what they want to a greater degree - look at http://pdos.csail.mit.edu/exo http://pdos.csail.mit.edu/exo http://en.wikipedia.org/wiki/Midori_(operating_system) http://en.wikipedia.org/wiki/Midori_(operating_system) Although I don't know much about midori