On Tue, Feb 14, 2012 at 12:21 PM, Fernando Lopez-Lezcano < [email protected]> wrote:
> On 02/14/2012 11:31 AM, Brian Monroe wrote: > >> I've been spending a lot of time on the #opensourcemusicians channel >> talking to Ubuntu Studio users about their kernel and latency times >> they're getting. Seems like most of them are using g a stock kernel with >> the preemptive option enabled and they are getting great latency results >> (2ms)while utilizing the @audio group on their user. I ended up >> compiling my own low latency kernel and I haven't had any issues with it >> yet. If this is what we are missing for the spin I'd be happy to >> maintain packaging for the kernel. I know ccrma has been behind a few >> kernel releases. >> > > The latest I have, current in testing is 3.2.2 + rt11 (for Fedora 15 and > 16). I am currently trying to build 3.2.6 + rt12. > Ah, that may have been an error on my part, I thought last I checked, which admittedly was a week and a half ago there was only a F15 kernel on the CCRMA website. > > The current rt not in testing is a 3.0.x based release (fc15/16). I have > not seen a big interest on being up to date - I just try to keep up with > the latest rt patch set. If there is more interest I could try to keep up > (but keeping up with _what_?, for a bit I was testing a 3.2 based rt > patched kernel and that was still not available for fc16 as an official > release). > > > I saw the instructions for adding the real time patch for a tick less >> kernel and from what I can tell it wouldn't be hard to get that rolling >> as well. >> >> I'm not entirely sure what ccrma does differently with their kernels >> compared to other Linux users, >> > > "compared to other Linux users"? I don't follow. Namely the Ubuntu Studio folks. Most users in #opensourcemusicians seem to use Ubuntu. Why? I don't know. > > > and I'm still a bit of a noob so I could >> be off base with this, but I would reason that we should be able to just >> utilize the same settings to archive similar performance enhancements. >> >> I thought I read that ccrma uses a unique scheduler, but if we could get >> a 2ms latency time without it, the point may be moot. >> > > Nope, no unique scheduler or other stuff. Where did you read that? (links > please?) > To be honest I'm not sure where I read this, but I do remember having conversations about it in one of the channels. Part of the reason I wanted to email the list was to hear what's what from the source, so thanks for clearing that up for me. > > The Planet CCRMA rt patched kernels are based on recent Fedora source > packages (usually from Koji) that are the closest I can find to the kernel > releases for which rt patches are available. To that source package I add > the rt patch, drop Fedora patches that are already included or conflict, > and built that. I use pretty much the stock Fedora kernel configuration > files except for whatever tweaks are necessary to enable the rt patch for > full preemption. That's about it. > Is there any help needed for testing/ect? I'm just trying to figure out what I can do to start contributing. > > As work in the rt patches has progressed the stock Fedora kernel (which is > basically upstream plus a few patches that have not been merge yet) has > become more and more usable for "normal" music work. For low latency work > (in a word, using your computer as a musical instrument), an rt patched > kernel still has an edge. Whether that really makes a difference depends on > your usage, your tolerance to occasional xruns and even the exact hardware > you are running on. > > -- Fernando >
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