On Apr 19, 2012, at 9:37 PM, Sean Cavanaugh <worksonmymach...@gmail.com> wrote:
> On 4/19/2012 10:00 PM, Jameson Ernst wrote: >> On Thursday, 19 April 2012 at 00:07:45 UTC, Sean Kelly wrote: >>> On Apr 18, 2012, at 4:06 PM, Andrew Lauritzen wrote: >>> >>>> I'm still interested in if anyone has any suggested workarounds or >>>> experience using Win32 fibers in D2 as well. >>> >>> The x32 Windows code should be pretty well tested. If this is using >>> the x64 code though, that's all quite new. I'll give this a try when I >>> find some time, but can't suggest a workaround offhand. It almost >>> sounds alignment-related, which could be tricky. >> >> Been following D for a while now, and fibers right in the std lib are a >> huge draw for me. I'm not an expert on them, but on the topic of x64 >> fibers, I have some exposure to them trying to contribute x64 windows >> support to bsnes, which uses its own home-grown fiber/coroutine system. >> >> Out of curiosity I took a look at the D fiber context code, and noticed >> that the x64 windows version doesn't seem to save the XMM6-15 registers >> (unless I missed it), which is something I forgot to do also. MSDN >> indicates that they are nonvolatile, which could potentially cause >> problems for FP heavy code on x64 windows. >> >> Not sure if I should file a bug for this, as I haven't tried an x64 >> windows fiber in D yet to make sure it's actually a problem first. > > Fibers seem like a last resort to me. They are fairly difficult to make > bulletproof due to the thread local storage issues and a few other problems > with context switches. Win7 scheduling and management of real threads is a > lot better than in previous versions, and in x64 mode there is also user mode > scheduling (UMS) system and the library built on top of it (ConcRT), which > gets you almost all of the benefits of fibers but you get to use 'real' > threads, plus the added bonus of being able to switch to another thread when > you stall on a page fault or block on a kernel object (something fiber's > can't do). I've thought about giving fibers their own TLS so D could have "real" user space threads. It would allow us to make the thread count in apps substantially higher if everything were a fiber and std.concurrency receive, for example, performed a context switch instead of blocking.
