https://bugs.wireshark.org/bugzilla/show_bug.cgi?id=3973
Summary: addresse hash is slow on little endian CPU.
Product: Wireshark
Version: SVN
Platform: All
OS/Version: All
Status: NEW
Severity: Minor
Priority: Low
Component: Wireshark
AssignedTo: wireshark-bugs@xxxxxxxxxxxxx
ReportedBy: dgautheron@xxxxxxxx
Build Information:
Paste the COMPLETE build information from "Help->About Wireshark", "wireshark
-v", or "tshark -v".
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Hi,
In epan/addr_resolv.c
The hostname cache uses the hash:
#define HASH_IPV4_ADDRESS(addr) ((addr) & (HASHHOSTSIZE - 1))
On little endian CPU (x86) it's slow because addr is in host order thus
'(addr) & (HASHHOSTSIZE - 1)' returns the network not the host.
I've found it while working on a capture with a lot of hosts, my old G4 (big
endian) was faster than a newer Pentium. As always O(n^2) beats Moore law.
Use
HASH_IPV4_ADDRESS(addr) (ipv4_get_net_order_addr(addr) & (HASHHOSTSIZE - 1))
or
HASH_IPV4_ADDRESS(addr) (g_htnol(addr) & (HASHHOSTSIZE - 1))
?
Didier
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