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+---
+title: "Per Thread Resources"
+weight: 2
+---
+
+# Per Thread Resources
+
+CSIT test framework is managing mapping of the following resources per thread:
+
+1. Cores, physical cores (pcores) allocated as pairs of sibling logical cores
+ (lcores) if server in HyperThreading/SMT mode, or as single lcores
+ if server not in HyperThreading/SMT mode. Note that if server's
+ processors are running in HyperThreading/SMT mode sibling lcores are
+ always used.
+2. Receive Queues (RxQ), packet receive queues allocated on each
+ physical and logical interface tested.
+3. Transmit Queues(TxQ), packet transmit queues allocated on each
+ physical and logical interface tested.
+
+Approach to mapping per thread resources depends on the application/DUT
+tested (VPP or DPDK apps) and associated thread types, as follows:
+
+1. Data-plane workers, used for data-plane packet processing, when no
+ feature workers present.
+
+ - Cores: data-plane workers are typically tested in 1, 2 and 4 pcore
+ configurations, running on single lcore per pcore or on sibling
+ lcores per pcore. Result is a set of {T}t{C}c thread-core
+ configurations, where{T} stands for a total number of threads
+ (lcores), and {C} for a total number of pcores. Tested
+ configurations are encoded in CSIT test case names,
+ e.g. "1c", "2c", "4c", and test tags "2T1C" (or "1T1C"), "4T2C"
+ (or "2T2C"), "8T4C" (or "4T4C").
+ - Interface Receive Queues (RxQ): as of CSIT-2106 release, number of
+ RxQs used on each physical or virtual interface is equal to the
+ number of data-plane workers. In other words each worker has a
+ dedicated RxQ on each interface tested. This ensures packet
+ processing load to be equal for each worker, subject to RSS flow
+ load balancing efficacy. Note: Before CSIT-2106 total number of
+ RxQs across all interfaces of specific type was equal to the
+ number of data-plane workers.
+ - Interface Transmit Queues (TxQ): number of TxQs used on each
+ physical or virtual interface is equal to the number of data-plane
+ workers. In other words each worker has a dedicated TxQ on each
+ interface tested.
+ - Applies to VPP and DPDK Testpmd and L3Fwd.
+
+2. Data-plane and feature workers (e.g. IPsec async crypto workers), the
+ latter dedicated to specific feature processing.
+
+ - Cores: data-plane and feature workers are tested in 2, 3 and 4
+ pcore configurations, running on single lcore per pcore or on
+ sibling lcores per pcore. This results in a two sets of
+ thread-core combinations separated by "-", {T}t{C}c-{T}t{C}c, with
+ the leading set denoting total number of threads (lcores) and
+ pcores used for data-plane workers, and the trailing set denoting
+ total number of lcores and pcores used for feature workers.
+ Accordingly, tested configurations are encoded in CSIT test case
+ names, e.g. "1c-1c", "1c-2c", "1c-3c", and test tags "2T1C_2T1C"
+ (or "1T1C_1T1C"), "2T1C_4T2C" (or "1T1C_2T2C"), "2T1C_6T3C"
+ (or "1T1C_3T3C").
+ - RxQ and TxQ: no RxQs and no TxQs are used by feature workers.
+ - Applies to VPP only.
+
+3. Management/main worker, control plane and management.
+
+ - Cores: single lcore.
+ - RxQ: not used (VPP default behaviour).
+ - TxQ: single TxQ per interface, allocated but not used (VPP default
+ behaviour).
+ - Applies to VPP only.
+
+## VPP Thread Configuration
+
+Mapping of cores and RxQs to VPP data-plane worker threads is done in
+the VPP startup.conf during test suite setup:
+
+1. `corelist-workers <list_of_cores>`: List of logical cores to run VPP
+ data-plane workers and feature workers. The actual lcores'
+ allocations depends on HyperThreading/SMT server configuration and
+ per test core configuration.
+
+ - For tests without feature workers, by default, all CPU cores
+ configured in startup.conf are used for data-plane workers.
+ - For tests with feature workers, CSIT code distributes lcores across
+ data-plane and feature workers.
+
+2. `num-rx-queues <value>`: Number of Rx queues used per interface.
+
+Mapping of TxQs to VPP data-plane worker threads uses the default VPP
+setting of one TxQ per interface per data-plane worker.
+
+## DPDK Thread Configuration
+
+Mapping of cores and RxQs to DPDK Testpmd/L3Fwd data-plane worker
+threads is done in the startup CLI:
+
+1. `-l <list_of_cores>` - List of logical cores to run DPDK
+ application.
+2. `nb-cores=<N>` - Number of forwarding cores.
+3. `rxq=<N>` - Number of Rx queues used per interface.