Hi Nicholas, On 1/4/2018 11:37 AM, Nicholas Mc Guire wrote: > On Thu, Jan 04, 2018 at 06:29:37PM +0000, Hindman, Gavin wrote: >> Since we seem to be in knowledge-sharing mode, is there an existing list of kernel config parameters, outside of those required to enable preempt_rt, known to impact or improve general system latency? I didn't find anything prowling the various wikis. >> > > Depending on what you mean with general system latency - > isolation related config items will allow you to improve the effectiveness > of pinning rt tasks to specific cores (e.g. cgroups) further > physical isolation like PALLOC (out of tree patch at > https://github.com/heechul/palloc) allow reducing cache side-effects > and L2/L3 sharing which can be a significant latency source. > of course these config items have no effect just by turning them on > but they allow to configure system software architectures that are > more suitable/robust for mixed rt/non-rt workloads. If you do have the option to use Intel hardware then please do consider Cache Allocation Technology (CAT) instead. With CAT it is possible to isolate portions of cache and assign cores or tasks to the different portions in order to control the amount of cache space into which these entities can fill. CAT thus provides hardware support for the isolation and prioritization of key tasks you seek. Additional benefits of CAT are that it is supported in the Linux kernel from v4.10 and there is no guessing needed from user space on which address bits determine cache sets (which is increasingly hard to do). More details about Linux support of CAT can be found in Documentation/x86/intel_rdt_ui.txt within the kernel source (v4.10+). A technical blog about the Linux implementation is at https://01.org/intel-rdt-linux/blogs/fyu1/2017/resource-allocation-intel%C2%AE-resource-director-technology Reinette -- 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
