Hey list, I have been experimenting with the nvidia blob, monitoring behavior / latencies, etc. Through some experimentation, googling/research and looking over previous nvidia-rt/compat patches from all over the interwebs; I've put together a few patches for the latest nvidia-331.20 driver. (probably portable to older 3xx.xx series too). You can obtain the patches from my Archlinux package (Arch User Repo) - download the package and extract the patches from the tarball. https://aur.archlinux.org/packages/nvidia-l-pa/ the PKGBUILD file, (which is a build script (for Arch/ABS pakcages) much like bsd/ports, gentoo /portage for those unfamiliar) shows how I patch/install the driver For Archlinux - although, obviously different distros do this different - so; DISCLAIMER: I'm not the person to ask for help :) --- 1. nvidia-rt_no_wbinvd.patch - It turns out that nvidia uses wbinvdt() <An intel instruction> that through it's operations, in a nutshell, ends up halting all cpus - which is the source of nearly all pain when using nvidia-rt. :\ ... WBINVD: http://www.jaist.ac.jp/iscenter-new/mpc/altix/altixdata/opt/intel/vtune/doc/users_guide/mergedProjects/analyzer_ec/mergedProjects/reference_olh/mergedProjects/instructions/instruct32_hh/vc323.htm nvidia-rt_no_wbinvd.patch disables that behavior. The patch is used along with (2.) nvidia-rt_explicit.patch <failing to do so will result in X not starting>, but the kernel module will still load. * expect an nvidia-rt/linux-rt system to report VERY impressive results in Cyclictest. (any places you used to see latency spikes should be reduced to almost (or) nothing. (ie: competative with OSS drivers). ---- 2. nvidia-rt_explicit.patch - i wrote this patch for nvidia-325.xx because skipping the PREEMPT_RT_FULL check, while resulting in a driver that could compile/install - it still deadlocked. So this patch just explicitly sets CONFIG_PREEMPT_RT_FULL (1). (which also allows the 1st patch to work). Lastly (but not needed to test the latency spikes, just use the above two); ---- 3. nvidia-rt_mutexes.patch - Lastly, as the name of the patch implies; this patch converts all of the semaphores in the nvidia driver into (regular) mutexes. Nvidia had moved some around some of the semaphore code in the 3xx.xx series, but i found them all. 1st off - * this patch will likely kill any scheduling type-bugs encountered when using the semaphore version. (i have yet to see any 'complaints' in the last few days of uptime). * (especially) this last patch I would (Please!) like someone with more experience to look at for me, if at all possible? It would be greatly appreciated -> I hack a bit, but am not an accomplished programmer, so making a rookie mistake is not out of the question. ~ That is why i do not have the feature enabled for users, as it is commented out.). That being said; I have tortured/tested the hell out of my system using the nvidia-rt_mutexes (all patches combined) and nvidia. (very deterministic, great cyclictest results, just fantastic). Anyway, I thought i should share, as i know there are some nvidia-rt users subbed to the list and my hope is someone can also review these patches, help fix them up, etc... as like i said - not much of a programmer, so expertise would be helpful ;) cheerz Jordan PS: I've also taken the time to 'rattle nvidia's cage' on this issue, feel free to pipe in on my thread, if you like; https://devtalk.nvidia.com/default/topic/654639/linux/nvidia-using-wbinvdt-lt-an-intel-instruction-gt-causes-huge-latency-spikes-/ -- To unsubscribe from this list: send the line "unsubscribe linux-rt-users" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
