Messages in this thread |  | | From | Reinette Chatre <> | Subject | [PATCH 0/3] x86/intel_rdt: Fix exclusive mode with CDP resources | Date | Wed, 26 Sep 2018 11:59:42 -0700 |
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Dear Maintainers,
CDP resources do not currently behave as expected when there are resource groups with mode 'exclusive'.
In the example below it was possible to create two resource groups, p1 and p2, that are both in exclusive mode but their usage of the underlying L2 cache actually overlaps.
root@glk:/sys/fs/resctrl# ls cpus cpus_list info mode p1 p2 schemata size tasks root@glk:/sys/fs/resctrl# cat schemata L2DATA:0=fff0 L2CODE:0=fff0 root@glk:/sys/fs/resctrl# cat mode shareable
root@glk:/sys/fs/resctrl# cat p1/schemata L2DATA:0=0003 L2CODE:0=000c root@glk:/sys/fs/resctrl# cat p1/mode exclusive
root@glk:/sys/fs/resctrl# cat p2/schemata L2DATA:0=000c L2CODE:0=0003 root@glk:/sys/fs/resctrl# cat p2/mode exclusive
root@glk:/sys/fs/resctrl# cat info/L2CODE/bit_usage 0=SSSSSSSSSSSSEEEE root@glk:/sys/fs/resctrl# cat info/L2DATA/bit_usage 0=SSSSSSSSSSSSEEEE root@glk:/sys/fs/resctrl#
In the above example, the CBM of L2DATA in p1 overlaps with the CBM of L2CODE in p2 while they are both in exclusive mode. While it may reflect no overlap among the L2DATA resources specifically it does actually imply overlap of use of the underlying hardware that is not the intention of 'exclusive' mode. This happens because the current implementation treats L2CODE and L2DATA as totally independent, when it is actually referring to the same underlying hardware.
This series fixes the potential for overlap of hardware resource use when resource groups are in 'exclusive' mode by ensuring that if there is a CDP peer on the same hardware then any overlap test would consider it also.
Allocations of data and code resources within the same exclusive resource group are allowed to overlap.
Your feedback will be greatly appreciated.
Reinette
Reinette Chatre (3): x86/intel_rdt: Introduce utility to obtain CDP peer x86/intel_rdt: CBM overlap should also check for overlap with CDP peer x86/intel_rdt: Fix initial allocation to consider CDP
arch/x86/kernel/cpu/intel_rdt_rdtgroup.c | 133 ++++++++++++++++++++++- 1 file changed, 128 insertions(+), 5 deletions(-)
-- 2.17.0
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