The Sub-NUMA cluster feature on some Intel processors partitions the CPUs
that share an L3 cache into two or more sets. This plays havoc with the
Resource Director Technology (RDT) monitoring features. Prior to this
patch Intel has advised that SNC and RDT are incompatible.
Some of these CPU support an MSR that can partition the RMID counters in
the same way. This allows monitoring features to be used. With the caveat
that users must be aware that Linux may migrate tasks more frequently
between SNC nodes than between "regular" NUMA nodes, so reading counters
from all SNC nodes may be needed to get a complete picture of activity
for tasks.
Cache and memory bandwidth allocation features continue to operate at
the scope of the L3 cache.
Signed-off-by: Tony Luck <tony.luck@xxxxxxxxx>
Changes since v12:
All:
Reinette - put commit tags in right order for TIP (Tested-by before
Reviewed-by)
Patch 7:
Fam Zheng - Check for -1 return from get_cpu_cacheinfo_id() and
increase size of bitmap tracking # of L3 instances.
Reinette - Add extra sanity checks. Note that this patch has
some additional tweaks beyond the e-mail discussion.
1) "3" is a valid return in addition to 1, 2, 4
2) Added a warning if the sanity checks fail that
prints number of CPU nodes and number of L3 cache
instances that were found.
Patch 8:
Babu - Fix grammar with an additional comma.
Tony Luck (8):
x86/resctrl: Prepare for new domain scope
x86/resctrl: Prepare to split rdt_domain structure
x86/resctrl: Prepare for different scope for control/monitor
operations
x86/resctrl: Split the rdt_domain and rdt_hw_domain structures
x86/resctrl: Add node-scope to the options for feature scope
x86/resctrl: Introduce snc_nodes_per_l3_cache
x86/resctrl: Sub NUMA Cluster detection and enable
x86/resctrl: Update documentation with Sub-NUMA cluster changes
Documentation/arch/x86/resctrl.rst | 25 +-
include/linux/resctrl.h | 85 +++--
arch/x86/include/asm/msr-index.h | 1 +
arch/x86/kernel/cpu/resctrl/internal.h | 66 ++--
arch/x86/kernel/cpu/resctrl/core.c | 433 +++++++++++++++++-----
arch/x86/kernel/cpu/resctrl/ctrlmondata.c | 58 +--
arch/x86/kernel/cpu/resctrl/monitor.c | 68 ++--
arch/x86/kernel/cpu/resctrl/pseudo_lock.c | 26 +-
arch/x86/kernel/cpu/resctrl/rdtgroup.c | 149 ++++----
9 files changed, 629 insertions(+), 282 deletions(-)
base-commit: 2cc14f52aeb78ce3f29677c2de1f06c0e91471ab
--
2.41.0
