tailscale/control
Brad Fitzpatrick db017d3b12 control/controlclient: remove quadratic allocs in mapSession
The mapSession code was previously quadratic: N clients in a netmap
send updates proportional to N and then for each, we do N units of
work. This removes most of that "N units of work" per update. There's
still a netmap-sized slice allocation per update (that's #8963), but
that's it.

Bit more efficient now, especially with larger netmaps:

                                 │     before     │                after                │
                                 │     sec/op     │   sec/op     vs base                │
    MapSessionDelta/size_10-8       47.935µ ±  3%   1.232µ ± 2%  -97.43% (p=0.000 n=10)
    MapSessionDelta/size_100-8      79.950µ ±  3%   1.642µ ± 2%  -97.95% (p=0.000 n=10)
    MapSessionDelta/size_1000-8    355.747µ ± 10%   4.400µ ± 1%  -98.76% (p=0.000 n=10)
    MapSessionDelta/size_10000-8   3079.71µ ±  3%   27.89µ ± 3%  -99.09% (p=0.000 n=10)
    geomean                          254.6µ         3.969µ       -98.44%

                                 │     before     │                after                 │
                                 │      B/op      │     B/op      vs base                │
    MapSessionDelta/size_10-8        9.651Ki ± 0%   2.395Ki ± 0%  -75.19% (p=0.000 n=10)
    MapSessionDelta/size_100-8      83.097Ki ± 0%   3.192Ki ± 0%  -96.16% (p=0.000 n=10)
    MapSessionDelta/size_1000-8     800.25Ki ± 0%   10.32Ki ± 0%  -98.71% (p=0.000 n=10)
    MapSessionDelta/size_10000-8   7896.04Ki ± 0%   82.32Ki ± 0%  -98.96% (p=0.000 n=10)
    geomean                          266.8Ki        8.977Ki       -96.64%

                                 │    before     │               after                │
                                 │   allocs/op   │ allocs/op   vs base                │
    MapSessionDelta/size_10-8         72.00 ± 0%   20.00 ± 0%  -72.22% (p=0.000 n=10)
    MapSessionDelta/size_100-8       523.00 ± 0%   20.00 ± 0%  -96.18% (p=0.000 n=10)
    MapSessionDelta/size_1000-8     5024.00 ± 0%   20.00 ± 0%  -99.60% (p=0.000 n=10)
    MapSessionDelta/size_10000-8   50024.00 ± 0%   20.00 ± 0%  -99.96% (p=0.000 n=10)
    geomean                          1.754k        20.00       -98.86%

Updates #1909

Change-Id: I41ee29358a5521ed762216a76d4cc5b0d16e46ac
Signed-off-by: Brad Fitzpatrick <bradfitz@tailscale.com>
2023-08-22 08:59:57 -07:00
..
controlbase various: add golangci-lint, fix issues (#7905) 2023-04-17 18:38:24 -04:00
controlclient control/controlclient: remove quadratic allocs in mapSession 2023-08-22 08:59:57 -07:00
controlhttp control/controlhttp: remove tstest.Clock from tests (#8830) 2023-08-09 15:03:22 -07:00
controlknobs all: update copyright and license headers 2023-01-27 15:36:29 -08:00