| Message ID | 20231116033405.185166-1-longman@redhat.com (mailing list archive) |
|---|---|
| Headers | show |
| Series | cgroup/cpuset: Improve CPU isolation in isolated partitions | expand |
On Wed, Nov 15, 2023 at 10:34:00PM -0500, Waiman Long wrote: > v4: > - Update patch 1 to move apply_wqattrs_lock() and apply_wqattrs_unlock() > down into CONFIG_SYSFS block to avoid compilation warnings. I already applied v3 to cgroup/for-6.8. Can you please send the fix up patch against that branch? Thanks.
On 11/19/23 10:23, Tejun Heo wrote: > On Wed, Nov 15, 2023 at 10:34:00PM -0500, Waiman Long wrote: >> v4: >> - Update patch 1 to move apply_wqattrs_lock() and apply_wqattrs_unlock() >> down into CONFIG_SYSFS block to avoid compilation warnings. > I already applied v3 to cgroup/for-6.8. Can you please send the fix up patch > against that branch? > Sure. I will post another fixup patch. Thanks, Longman
v4: - Update patch 1 to move apply_wqattrs_lock() and apply_wqattrs_unlock() down into CONFIG_SYSFS block to avoid compilation warnings. v3: - Break out a separate patch to make workqueue_set_unbound_cpumask() static and move it down to the CONFIG_SYSFS section. - Remove the "__DEBUG__." prefix and the CFTYPE_DEBUG flag from the new root only cpuset.cpus.isolated control files and update the test accordingly. v2: - Add 2 read-only workqueue sysfs files to expose the user requested cpumask as well as the isolated CPUs to be excluded from wq_unbound_cpumask. - Ensure that caller of the new workqueue_unbound_exclude_cpumask() hold cpus_read_lock. - Update the cpuset code to make sure the cpus_read_lock is held whenever workqueue_unbound_exclude_cpumask() may be called. Isolated cpuset partition can currently be created to contain an exclusive set of CPUs not used in other cgroups and with load balancing disabled to reduce interference from the scheduler. The main purpose of this isolated partition type is to dynamically emulate what can be done via the "isolcpus" boot command line option, specifically the default domain flag. One effect of the "isolcpus" option is to remove the isolated CPUs from the cpumasks of unbound workqueues since running work functions in an isolated CPU can be a major source of interference. Changing the unbound workqueue cpumasks can be done at run time by writing an appropriate cpumask without the isolated CPUs to /sys/devices/virtual/workqueue/cpumask. So one can set up an isolated cpuset partition and then write to the cpumask sysfs file to achieve similar level of CPU isolation. However, this manual process can be error prone. This patch series implements automatic exclusion of isolated CPUs from unbound workqueue cpumasks when an isolated cpuset partition is created and then adds those CPUs back when the isolated partition is destroyed. There are also other places in the kernel that look at the HK_FLAG_DOMAIN cpumask or other HK_FLAG_* cpumasks and exclude the isolated CPUs from certain actions to further reduce interference. CPUs in an isolated cpuset partition will not be able to avoid those interferences yet. That may change in the future as the need arises. Waiman Long (5): workqueue: Make workqueue_set_unbound_cpumask() static workqueue: Add workqueue_unbound_exclude_cpumask() to exclude CPUs from wq_unbound_cpumask selftests/cgroup: Minor code cleanup and reorganization of test_cpuset_prs.sh cgroup/cpuset: Keep track of CPUs in isolated partitions cgroup/cpuset: Take isolated CPUs out of workqueue unbound cpumask Documentation/admin-guide/cgroup-v2.rst | 10 +- include/linux/workqueue.h | 2 +- kernel/cgroup/cpuset.c | 286 +++++++++++++----- kernel/workqueue.c | 165 +++++++--- .../selftests/cgroup/test_cpuset_prs.sh | 216 ++++++++----- 5 files changed, 475 insertions(+), 204 deletions(-)