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DXR maintains compressed lookup structures with a trivial search procedure. A two-stage trie is indexed by the more significant bits of the search key (IPv4 address), while the remaining bits are used for finding the next hop in a sorted array. The tradeoff between memory footprint and search speed depends on the split between the trie and the remaining binary search. The default of 20 bits of the key being used for trie indexing yields good performance (see below) with footprints of around 2.5 Bytes per prefix with current BGP snapshots. Rebuilding lookup structures takes some time, which is compensated for by batching several RIB change requests into a single FIB update, i.e. FIB synchronization with the RIB may be delayed for a fraction of a second. RIB to FIB synchronization, next-hop table housekeeping, and lockless lookup capability is provided by the FIB_ALGO infrastructure. DXR works well on modern CPUs with several MBytes of caches, especially in VMs, where is outperforms other currently available IPv4 FIB algorithms by a large margin. Synthetic single-thread LPM throughput test method: kldload test_lookup; kldload dpdk_lpm4; kldload fib_dxr sysctl net.route.test.run_lps_rnd=N sysctl net.route.test.run_lps_seq=N where N is the number of randomly generated keys (IPv4 addresses) which should be chosen so that each test iteration runs for several seconds. Each reported score represents the best of three runs, in million lookups per second (MLPS), for two bechmarks (RND & SEQ) with two FIBs: host: single interface address, local subnet route + default route BGP: snapshot from linx.routeviews.org, 887957 prefixes, 496 next hops Bhyve VM on an Intel(R) Xeon(R) CPU E5-2670 0 @ 2.60 GHz: inet.algo host, RND host, SEQ BGP, RND BGP, SEQ bsearch4 40.6 20.2 N/A N/A radix4 7.8 3.8 1.2 0.6 radix4_lockless 18.0 9.0 1.6 0.8 dpdk_lpm4 14.4 5.0 14.6 5.0 dxr 70.3 34.7 43.0 19.5 Intel(R) Core(TM) i5-5300U CPU @ 2.30 GHz: inet.algo host, RND host, SEQ BGP, RND BGP, SEQ bsearch4 47.0 23.1 N/A N/A radix4 8.5 4.2 1.9 1.0 radix4_lockless 19.2 9.5 2.5 1.2 dpdk_lpm4 31.2 9.4 31.6 9.3 dxr 84.9 41.4 51.7 23.6 Intel(R) Core(TM) i7-4771 CPU @ 3.50 GHz: inet.algo host, RND host, SEQ BGP, RND BGP, SEQ bsearch4 59.5 29.4 N/A N/A radix4 10.8 5.5 2.5 1.3 radix4_lockless 24.7 12.0 3.1 1.6 dpdk_lpm4 29.1 9.0 30.2 9.1 dxr 101.3 49.9 69.8 32.5 AMD Ryzen 7 3700X 8-Core Processor @ 3.60 GHz: inet.algo host, RND host, SEQ BGP, RND BGP, SEQ bsearch4 70.8 35.4 N/A N/A radix4 14.4 7.2 2.8 1.4 radix4_lockless 30.2 15.1 3.7 1.8 dpdk_lpm4 29.9 9.0 30.0 8.9 dxr 163.3 81.5 99.5 44.4 AMD Ryzen 5 5600X 6-Core Processor @ 3.70 GHz: inet.algo host, RND host, SEQ BGP, RND BGP, SEQ bsearch4 93.6 46.7 N/A N/A radix4 18.9 9.3 4.3 2.1 radix4_lockless 37.2 18.6 5.3 2.7 dpdk_lpm4 51.8 15.1 51.6 14.9 dxr 218.2 103.3 114.0 49.0 Reviewed by: melifaro MFC after: 1 week Differential Revision: https://reviews.freebsd.org/D29821
FreeBSD Source:
This is the top level of the FreeBSD source directory.
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Source Roadmap:
| Directory | Description |
|---|---|
| bin | System/user commands. |
| cddl | Various commands and libraries under the Common Development and Distribution License. |
| contrib | Packages contributed by 3rd parties. |
| crypto | Cryptography stuff (see crypto/README). |
| etc | Template files for /etc. |
| gnu | Various commands and libraries under the GNU Public License. Please see gnu/COPYING and gnu/COPYING.LIB for more information. |
| include | System include files. |
| kerberos5 | Kerberos5 (Heimdal) package. |
| lib | System libraries. |
| libexec | System daemons. |
| release | Release building Makefile & associated tools. |
| rescue | Build system for statically linked /rescue utilities. |
| sbin | System commands. |
| secure | Cryptographic libraries and commands. |
| share | Shared resources. |
| stand | Boot loader sources. |
| sys | Kernel sources. |
sys/arch/conf |
Kernel configuration files. GENERIC is the configuration used in release builds. NOTES contains documentation of all possible entries. |
| tests | Regression tests which can be run by Kyua. See tests/README for additional information. |
| tools | Utilities for regression testing and miscellaneous tasks. |
| usr.bin | User commands. |
| usr.sbin | System administration commands. |
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