On Tue, 5 Sep 2017 17:35:16 +0100 (BST) "[email protected]" <[email protected]> wrote:
> Hi all, > I'm running a DPDK transmit thread with the ixgbe PMD on Ubuntu 17.04, with > dual Xeon E5-2623 v4 CPUs on an Intel S2600 motherboard. The cores in use by > DPDK are isolated in the boot cmdline with "isolcpus" > What I'm observing is I believe, on occasion, the DPDK transmit thread being > descheduled by the system for between 20 and 60 milliseconds. > I've tried running as Real time with max priority, and tweaking the > scheduling through /proc/sys/kernel/sched_rt_runtime_us to be 99.999% > available for real time thread, but so far no improvement > I notice there are various kernel threads resident on the isolated cpus, > cpuhp/watchdog/migration/ksoftirqd +multiple kworker threads. > I can only assume the system is occasionally running these kernel side > instead, although the CPU time taken (tens of milliseconds) seems very high. > Note please that I amd NOT running with a modified kernel (nohz_full is not > set). > Does anyone have any advice to keep the DPDK transmit thread running for more > of the time on this SMP system ? > Many thanks > Terry. Probably not a Linux scheduler issue. More likely some system hardware thing like SMT or ME.
