On Tue, Jul 20, 2021 at 10:18:31AM -0400, Waiman Long wrote: > Bugzilla: https://bugzilla.redhat.com/show_bug.cgi?id=TBD > > commit 994fb794cb252edd124a46ca0994e37a4726a100 > Author: Waiman Long <longman@xxxxxxxxxx> > Date: Sat, 19 Jun 2021 13:28:19 -0400 > > cgroup/cpuset: Add a new isolated cpus.partition type > > Cpuset v1 uses the sched_load_balance control file to determine if load > balancing should be enabled. Cpuset v2 gets rid of sched_load_balance > as its use may require disabling load balancing at cgroup root. > > For workloads that require very low latency like DPDK, the latency > jitters caused by periodic load balancing may exceed the desired > latency limit. > > When cpuset v2 is in use, the only way to avoid this latency cost is to > use the "isolcpus=" kernel boot option to isolate a set of CPUs. After > the kernel boot, however, there is no way to add or remove CPUs from > this isolated set. For workloads that are more dynamic in nature, that > means users have to provision enough CPUs for the worst case situation > resulting in excess idle CPUs. > > To address this issue for cpuset v2, a new cpuset.cpus.partition type > "isolated" is added which allows the creation of a cpuset partition > without load balancing. This will allow system administrators to > dynamically adjust the size of isolated partition to the current need > of the workload without rebooting the system. > > Signed-off-by: Waiman Long <longman@xxxxxxxxxx> > > Signed-off-by: Waiman Long <longman@xxxxxxxxxx> Nice! And while we are adding a new ABI, can we take advantage of that and add a specific semantic that if a new isolated partition matches a subset of "isolcpus=", it automatically maps to it. This means that any further modification to that isolated partition will also modify the associated isolcpus= subset. Or to summarize, when we create a new isolated partition, remove the associated CPUs from isolcpus= ? Thanks.
