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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.