Wireshark mailing list archives
Re: Timestamp Skew
From: "Gianluca Varenni" <gianluca.varenni () cacetech com>
Date: Fri, 15 Jan 2010 15:56:44 -0800
-------------------------------------------------- From: "Guy Harris" <guy () alum mit edu> Sent: Friday, January 15, 2010 3:20 PM To: "Community support list for Wireshark" <wireshark-users () wireshark org> Subject: Re: [Wireshark-users] Timestamp Skew
On Jan 15, 2010, at 3:04 PM, Gianluca Varenni wrote:It's not documented, and depends on the version of Windows, the service pack, and the HAL type... Most of the times it's a non-compensated RDTSC, however.If it's just RDTSC, wouldn't it have the same problems on "SpeedStep machines" as raw RDTSC? The description in the mail was
The documentation for KeQueryPerformanceCounter doesn't say anything about that. So it's entirely possible that they do something under the hood to prevent this issue. Have a nice day GV
Possible values are a.. 0 (default) -> Timestamps generated through KeQueryPerformanceCounter, less reliable on SMP/HyperThreading machines, precision = some microseconds b.. 2 -> Timestamps generated through KeQuerySystemTime, more reliable on SMP/HyperThreading machines, precision = scheduling quantum (10/15 ms) c.. 3 -> Timestamps generated through the i386 instruction RDTSC, less reliable on SMP/HyperThreading/SpeedStep machines, precision = some microsecondsAlso, should it say "machines where the clock rate is variable" or something such as that? I don't know whether Intel still calls it "SpeedStep", and AMD have their own names for it. ___________________________________________________________________________ Sent via: Wireshark-users mailing list <wireshark-users () wireshark org> Archives: http://www.wireshark.org/lists/wireshark-users Unsubscribe: https://wireshark.org/mailman/options/wireshark-users mailto:wireshark-users-request () wireshark org?subject=unsubscribe
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Current thread:
- Re: Timestamp Skew, (continued)
- Re: Timestamp Skew Bill Meier (Jan 14)
- Re: Timestamp Skew Gianluca Varenni (Jan 14)
- Re: Timestamp Skew Lee Riemer (Jan 14)
- Re: Timestamp Skew Gianluca Varenni (Jan 14)
- Re: Timestamp Skew Lee Riemer (Jan 14)
- Re: Timestamp Skew Gianluca Varenni (Jan 14)
- Re: Timestamp Skew Tamás Varga (Jan 15)
- Re: Timestamp Skew Guy Harris (Jan 15)
- Re: Timestamp Skew Gianluca Varenni (Jan 15)
- Re: Timestamp Skew Guy Harris (Jan 15)
- Re: Timestamp Skew Gianluca Varenni (Jan 15)