https://bugs.wireshark.org/bugzilla/show_bug.cgi?id=4956
Summary: The 5th dec place in all SRT dialogs is sometimes
inaccurate; ans need for 6 dec places of SRT precision
Product: Wireshark
Version: 1.5.x (Experimental)
Platform: All
OS/Version: All
Status: NEW
Severity: Normal
Priority: Low
Component: Wireshark
AssignedTo: wireshark-bugs@xxxxxxxxxxxxx
ReportedBy: turney_cal@xxxxxxx
CC: turney_cal@xxxxxxx
Cal Turney <turney_cal@xxxxxxx> changed:
What |Removed |Added
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Attachment #4860| |review_for_checkin?
Flag| |
Created an attachment (id=4860)
--> (https://bugs.wireshark.org/bugzilla/attachment.cgi?id=4860)
Patches to service_response_time_table.c and rpc_progs.c
Build Information:
Version 1.5.0-SVN-33316
Copyright 1998-2010 Gerald Combs <gerald@xxxxxxxxxxxxx> and contributors.
This is free software; see the source for copying conditions. There is NO
warranty; not even for MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
Compiled with GTK+ 2.16.6, (32-bit) with GLib 2.22.4, with WinPcap (version
unknown), with libz 1.2.3, without POSIX capabilities, without libpcre, with
SMI
0.4.8, with c-ares 1.7.1, with Lua 5.1, without Python, with GnuTLS 2.8.5, with
Gcrypt 1.4.5, with MIT Kerberos, with GeoIP, with PortAudio V19-devel (built
Jun
26 2010), with AirPcap.
Running on Windows XP Service Pack 3, build 2600, with WinPcap version 4.1.1
(packet.dll version 4.1.0.1753), based on libpcap version 1.0 branch 1_0_rel0b
(20091008), GnuTLS 2.8.5, Gcrypt 1.4.5, without AirPcap.
Built using Microsoft Visual C++ 9.0 build 30729
--
1.) SRT values are currently displayed in 10 microseconds (10us) but with the
emergence of 10GigE networks, one microsecond (1us) accuracy is increasingly
required for addressing network performance issues.
2.) The 5th decimal place of the average SRT values in all SRT dialogs is
sometimes 1us too small due to rounding error. In
service_response_time_table.c and rpc_progs.c, the 'tot.nsecs' variable is
divided by 10,000, and the result is divided by the number of calls. The
resulting value is in units of 10us. For example, if the total number of
nanoseconds (tot.nsecs) is 239,999, and the number of calls (num) is 2, the
average SRT using this formula is 11 10us units or 0.00011 (239,999/10,000=23,
23/2=11);however, the correct number is 12 or 0.00012.
A simple solution is to divide 'tot.nsecs' by the number of calls, add 500, and
divide the result by 10,000 which, in the above case, results in 12 (239,999
/2=119,999, 119,999+500=120,499, 120,499/10,000=12) or 0.00012.
--
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