Hey folks, The latency changes sound relevant to some work on the scheduler I'm doing; is there a place I can see the changes?
Thanks, Edward Excerpts from Simon Peyton-Jones's message of Wed Feb 06 10:10:10 -0800 2013: > I (with help from Kazu and helpful comments from Bryan and Johan) have nearly > completed an overhaul to the IO manager based on my observations and we are > in the final stages of getting it into GHC > > This is really helpful. Thank you very much Andreas, Kazu, Bryan, Johan. > > Simon > > From: parallel-hask...@googlegroups.com > [mailto:parallel-hask...@googlegroups.com] On Behalf Of Andreas Voellmy > Sent: 06 February 2013 14:28 > To: watson.timo...@gmail.com > Cc: kosti...@gmail.com; parallel-haskell; glasgow-haskell-users@haskell.org > Subject: Re: Cloud Haskell and network latency issues with -threaded > > Hi all, > > I haven't followed the conversations around CloudHaskell closely, but I > noticed the discussion around latency using the threaded runtime system, and > I thought I'd jump in here. > > I've been developing a server in Haskell that serves hundreds to thousands of > clients over very long-lived TCP sockets. I also had latency problems with > GHC. For example, with 100 clients I had a 10 ms (millisecond) latency and > with 500 clients I had a 29ms latency. I looked into the problem and found > that some bottlenecks in the threaded IO manager were the cause. I made some > hacks there and got the latency for 100 and 500 clients down to under 0.2 ms. > I (with help from Kazu and helpful comments from Bryan and Johan) have nearly > completed an overhaul to the IO manager based on my observations and we are > in the final stages of getting it into GHC. Hopefully our work will also fix > the latency issues in CloudHaskell programs :) > > It would be very helpful if someone has some benchmark CloudHaskell > applications and workloads to test with. Does anyone have these handy? > > Cheers, > Andi > > On Wed, Feb 6, 2013 at 9:09 AM, Tim Watson > <watson.timo...@gmail.com<mailto:watson.timo...@gmail.com>> wrote: > Hi Kostirya, > > I'm putting the parallel-haskell and ghc-users lists on cc, just in case > other (better informed) folks want to chip in here. > > ---- > > First of all, I'm assuming you're talking about network latency when > compiling with -threaded - if not I apologise for misunderstanding! > > There is apparently an outstanding network latency issue when compiling with > -threaded, but according to a conversation I had with the other developers on > #haskell-distributed, this is not something that's specific to Cloud Haskell. > It is something to do with the threaded runtime system, so would need to be > solved for GHC (or is it just the Network package!?) in general. Writing up a > simple C program and equivalent socket use in Haskell and comparing the > latency using -threaded will show this up. > > See the latency section in > http://haskell-distributed.github.com/wiki/networktransport.html for some > more details. According to that, there *are* some things we might be able to > do, but the 20% latency isn't going to change significantly on the face of > things. > > We have an open ticket to look into this > (https://cloud-haskell.atlassian.net/browse/NTTCP-4) and at some point we'll > try and put together the sample programs in a github repository (if that's > not already done - I might've missed previous spikes done by Edsko or others) > and investigate further. > > One of the other (more experienced!) devs might be able to chip in and > proffer a better explanation. > > Cheers, > Tim > > On 6 Feb 2013, at 13:27, kosti...@gmail.com<mailto:kosti...@gmail.com> wrote: > > > Haven't you had a necessity to launch Haskell in no-threaded mode during > > the intense network data exchange? > > I am getting the double performance penalty in threaded mode. But I must > > use threaded mode because epoll and kevent are available in the threaded > > mode only. > > > > [snip] > > > > > > > среда, 6 февраля 2013 г., 12:33:36 UTC+2 пользователь Tim Watson написал: > > Hello all, > > > > It's been a busy week for Cloud Haskell and I wanted to share a few of > > our news items with you all. > > > > Firstly, we have a new home page at http://haskell-distributed.github.com, > > into which most of the documentation and wiki pages have been merged. Making > > sassy looking websites is not really my bag, so I'm very grateful to the > > various author's whose Creative Commons licensed designs and layouts made > > it easy to put together. We've already had some pull requests to fix minor > > problems on the site, so thanks very much to those who've contributed > > already! > > > > As well as the new site, you will find a few of us hanging out on the > > #haskell-distributed channel on freenode. Please do come along and join in > > the conversation. > > > > We also recently split up the distributed-process project into separate > > git repositories, one for each component that makes up Cloud Haskell. This > > was done partly for administrative purposes and partly because we're in the > > process of setting up CI builds for all the projects. > > > > Finally, we've moved from Github's issue tracker to a hosted Jira/Bamboo > > setup > > at https://cloud-haskell.atlassian.net - pull requests are naturally still > > welcome > > via Github! Although you can browse issues freely without logging in, you > > will > > need to provide an email address and get an account in order to submit new > > ones. > > If you have any difficulties logging in, please don't hesitate to contact me > > directly, via this forum or the cloud-haskell-developers mailing list (on > > google groups). > > > > As always, we'd be delighted to hear any feedback! > > > > Cheers, > > Tim > _______________________________________________ Glasgow-haskell-users mailing list Glasgow-haskell-users@haskell.org http://www.haskell.org/mailman/listinfo/glasgow-haskell-users
