29.05.2012 07:01, Bart Oldeman wrote: > I now realise that the person who sent you the mail must have missed > the message: > > Using CPU emulation because vm.mmap_min_addr > 0. > For more information, see /home/bart/.dosemu/boot.log. Wait, wait, haven't YOU changed this to warning, so that it doesn't appear to the terminal? So he missed it. I think it have to be returned.
>> On a side note, IIRC the qemu people claim that the jit codegen >> can be as fast (or faster) than the vm86. Any ideas why this is >> not the case with dosemu? :) > It just isn't. And of course it doesn't make sense, a jit always has > more overhead than native execution. The main point is the IO, priv instructions and interrupts that are causing an exception, the switch to the monitor, the instruction decoding, and then the emulation! That is what makes vm86 slow, and this is where the jit can be much faster. And certainly on the flat-usermode code the vm86 will be a lot faster than any jit. Concerning dosemu, I can think of 2 things: 1. jit just mimics the vm86() semantic, so, on any IO or the priv insn it just returns to the monitor. If we are going to be fast, the jit will have to link all the handling routines directly to the generated code. But I am not suggesting such a change, because this will be too much of a work, and dosemu will look entirely different after. This is a subject for another project, and there is already a dosbox anyway. 2. The guy was using the EMS multitasker, and you haven't yet made the e_invalidate() to do the right thing, so he had a lot of faults. > Anyway, the main question is, is it fast enough? Since most of the > more speed-demanding DOS apps use DPMI which can be natively executed, > and even with a factor 20 slowdown on a synthetic benchmark, the JIT > on a 2 GHz PC is still like a 100 MHz Pentium, quite a powerful > machine in DOS days. But dosemu is doing too much after the switch from the DOS code. Its main loop is just huge. If it is trimmed, and if there are no faults on the cpuemu code, then maybe the guy who complained, will get the reasonable speed. But cleaning up the main dosemu loop is a big task... ------------------------------------------------------------------------------ Live Security Virtual Conference Exclusive live event will cover all the ways today's security and threat landscape has changed and how IT managers can respond. Discussions will include endpoint security, mobile security and the latest in malware threats. http://www.accelacomm.com/jaw/sfrnl04242012/114/50122263/ _______________________________________________ Dosemu-devel mailing list Dosemu-devel@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/dosemu-devel
