Recently a lot of work has been done in the kernel to be able to keep OS threads off low latency cores with the NOHZ work mainly pushed by Frederic Weisbecker (also also Paul McKenney modifying RCU for that purpose). With that approach we may now reduce the timer tick to a frequency of 1 per second. The result of that work is now available in Redhat 7. I have recently submitted work on the vmstat kworkers that makes the kworkers run on demand with a shepherd worker checking from a non low latency processor if there is actual work to be done on a processor in low latency mode. If not then the kworker requests can be avoided and therefore activities on that processor are reduced. This approach can be extended to cover other necessary activities on low latency cores. There is other work in progress to limit unbound kworker threads to no NOHZ processors. Also more work is in flight to work on various issues in the scheduler to enable us to hold off the timer tick for more than one second. There are numerous other issues that can impact on a low latency core from the memory management system. I would like to discuss ways that we can further ensure that OS activities do not impact latency critical threads running on special nohz cores. This may cover: - minor and major faults and how to suppress them effectively. - Processor cache impacts by sibling threads. - IPIs - Control over various subsystem specific per cpu threads. - Control impacts of scans for defragmentation and THP on these cores. There was a recent discussion on the subject matter on lkml that mentions a number of the pending issues in this area: https://lkml.org/lkml/2014/11/11/679 https://lkml.org/lkml/2014/10/31/364 -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@xxxxxxxxx. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: <a href=mailto:"dont@xxxxxxxxx";> email@xxxxxxxxx </a>