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| author |   Coco Li <lixiaoyan@google.com> | 2023-11-29 07:27:52 +0000 |
|---|---|---|
| committer |   David S. Miller <davem@davemloft.net> | 2023-12-02 22:24:36 +0000 |
| commit | 14006f1d8fa24a2320781ad503ca1cba92e940d2 (patch) | |
| tree | 9ea58cc8169735713cd5b9b16334e2fdfccc97bf /Documentation/networking/index.rst | |
| parent | nfp: ethtool: expose transmit SO_TIMESTAMPING capability (diff) | |
| download | linux-14006f1d8fa24a2320781ad503ca1cba92e940d2.tar.xz linux-14006f1d8fa24a2320781ad503ca1cba92e940d2.zip | |
Documentations: Analyze heavily used Networking related structs
Analyzed a few structs in the networking stack by looking at variables
within them that are used in the TCP/IP fast path.
Fast path is defined as TCP path where data is transferred from sender to
receiver unidirectionally. It doesn't include phases other than
TCP_ESTABLISHED, nor does it look at error paths.
We hope to re-organizing variables that span many cachelines whose fast
path variables are also spread out, and this document can help future
developers keep networking fast path cachelines small.
Optimized_cacheline field is computed as
(Fastpath_Bytes/L3_cacheline_size_x86), and not the actual organized
results (see patches to come for these).
Investigation is done on 6.5
Name Struct_Cachelines Cur_fastpath_cache Fastpath_Bytes Optimized_cacheline
tcp_sock 42 (2664 Bytes) 12 396 8
net_device 39 (2240 bytes) 12 234 4
inet_sock 15 (960 bytes) 14 922 14
Inet_connection_sock 22 (1368 bytes) 18 1166 18
Netns_ipv4 (sysctls) 12 (768 bytes) 4 77 2
linux_mib 16 (1060) 6 104 2
Note how there isn't much improvement space for inet_sock and
Inet_connection_sock because sk and icsk_inet respectively takes up so
much of the struct that rest of the variables become a small portion of
the struct size.
So, we decided to reorganize tcp_sock, net_device, netns_ipv4
Suggested-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: Coco Li <lixiaoyan@google.com>
Reviewed-by: Eric Dumazet <edumazet@google.com>
Reviewed-by: Shakeel Butt <shakeelb@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Diffstat (limited to 'Documentation/networking/index.rst')
| -rw-r--r-- | Documentation/networking/index.rst | 1 |
1 files changed, 1 insertions, 0 deletions
diff --git a/Documentation/networking/index.rst b/Documentation/networking/index.rst index d9424dcb19bf..69f3d6dcd9fd 100644 --- a/Documentation/networking/index.rst +++ b/Documentation/networking/index.rst @@ -75,6 +75,7 @@ Contents: mptcp-sysctl multiqueue napi + net_cachelines/index netconsole netdev-features netdevices |