On 11 June 2010 16:02, Steven McCoy <span dir="ltr"><<a href="mailto:steven.mccoy@miru.hk">steven.mccoy@miru.hk</a>></span> wrote:<br><div class="gmail_quote"><blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex;">

<div class="im">I've only seen the worst case scenario, like the 16ms timing in Windows, nothing much about Nehalem or event the Red Hat vsyscall other than they are "better".</div><div class="gmail_quote">

<div><br></div></div></blockquote><div><br></div><div>The Red Hat detail,</div><div><br></div><div><a href="http://www.redhat.com/docs/en-US/Red_Hat_Enterprise_MRG/1.0/html/Realtime_Tuning_Guide/sect-Realtime_Tuning_Guide-Realtime_Specific_Tuning-RT_Specific_gettimeofday_speedup.html">http://www.redhat.com/docs/en-US/Red_Hat_Enterprise_MRG/1.0/html/Realtime_Tuning_Guide/sect-Realtime_Tuning_Guide-Realtime_Specific_Tuning-RT_Specific_gettimeofday_speedup.html</a></div>

<div><br></div><div><br></div><div>This older article on Oracle seems more informative,</div><div><br></div><div><a href="http://kevinclosson.wordpress.com/2007/01/24/gettimeofday-and-oracle-on-amd-processors/">http://kevinclosson.wordpress.com/2007/01/24/gettimeofday-and-oracle-on-amd-processors/</a></div>

<div><br></div><div>"<span class="Apple-style-span" style="font-family: 'Lucida Grande', Verdana, Arial, sans-serif; font-size: 12px; color: rgb(68, 68, 68); line-height: 21px; ">It takes 324 cycles per call to complete 1 million GTOD calls without RDTSCP and 221 cycles per call with the capability."</span></div>

<div><br></div><div>Referencing this article,</div><div><br></div><div><a href="http://developer.amd.com/documentation/articles/Pages/1214200692.aspx">http://developer.amd.com/documentation/articles/Pages/1214200692.aspx</a></div>

<div><br></div><div><a href="http://www.redhat.com/docs/en-US/Red_Hat_Enterprise_MRG/1.0/html/Realtime_Tuning_Guide/sect-Realtime_Tuning_Guide-Realtime_Specific_Tuning-RT_Specific_gettimeofday_speedup.html"></a>-- </div>
<div>
Steve-o </div></div>