4 ms·

It is sometimes a bit disheartening to see so much development effort go toward the virtualization/KVM/Xen side rather than seeing improvements in TCG. I realiz

by moyix 13y ago

It is sometimes a bit disheartening to see so much development effort go toward the virtualization/KVM/Xen side rather than seeing improvements in TCG. I realize that Redhat (and maybe others?) funds a lot of development in that area, so it's natural that that's where most of the improvements are. I mostly use QEMU as a CPU emulator, though, and it's frustrating to see so little activity on the TCG side, especially when it comes to things like bugfixes (Win7 x64 bluescreens under TCG, mipsel loadvm broken, to name two issues that have bitten me). Still, kudos to the developers for making some things better (TCG actually does seem noticeably faster in 2.0.0) and congratulations on the 2.0.0 release!

pm215 13y ago
Yes, I think Richard Henderson put in some effort in optimising TCG, which has helped. My take on the KVM vs TCG split is simply that in the end open source projects are driven by the people who put in the work, and inevitably if there's a set of people whose day job is to work on the project then it's going to tend to improve in the areas those people and companies need. And in general the people working on the emulation side of things seem to be happy enough with the performance levels we currently have: I see plenty of patches to add new ARM boards or fix issues with devices, or to fix bugs in the linux-user emulation code. In comparison, there doesn't really seem to be much interest in TCG performance (and serious improvements in performance, though possible, would be a six month or longer project to achieve). The particular bugs you note are even further out in the cold since x86 guest TCG in particular is pretty much orphaned and MIPS is not a great deal better (though I have been heartened to see recent contributions from Imagination).
dorfsmay 13y ago
TCG?
- ris 13y ago
  "Tiny Code Generator", the JIT for cross architecture emulation.

by moyix 13y ago

pm215 13y ago

Yes, I think Richard Henderson put in some effort in optimising TCG, which has helped. My take on the KVM vs TCG split is simply that in the end open source projects are driven by the people who put in the work, and inevitably if there's a set of people whose day job is to work on the project then it's going to tend to improve in the areas those people and companies need. And in general the people working on the emulation side of things seem to be happy enough with the performance levels we currently have: I see plenty of patches to add new ARM boards or fix issues with devices, or to fix bugs in the linux-user emulation code. In comparison, there doesn't really seem to be much interest in TCG performance (and serious improvements in performance, though possible, would be a six month or longer project to achieve). The particular bugs you note are even further out in the cold since x86 guest TCG in particular is pretty much orphaned and MIPS is not a great deal better (though I have been heartened to see recent contributions from Imagination).

dorfsmay 13y ago

TCG?

ris 13y ago
"Tiny Code Generator", the JIT for cross architecture emulation.