From mboxrd@z Thu Jan 1 00:00:00 1970 From: jeremie.galarneau@efficios.com (=?UTF-8?Q?J=C3=A9r=C3=A9mie_Galarneau?=) Date: Fri, 3 Apr 2015 10:22:05 -0400 Subject: [lttng-dev] major variations in perfomance figures In-Reply-To: References: Message-ID: On Tue, Mar 31, 2015 at 3:46 PM, Wolfgang Rostek wrote: > Hi all, > > I did a first perfomance test extending the demo example > by tracing 30 simple integers in a loop. > > For a similar CPU (i5 quad core 2.8GHz) I saw values > mentioned around 250ns in the forum. > > I've tried the test several time and could come down > to about 350ns. The machine was almost idle for all > tests. > > What makes me wonder is a large variation with frequent > runs giving me 750-800ns. > > Not the absolute time but the variations isn't clear > to me. From my understanding the caller path is more > or less straight to shared memory. Why do different > runs show more than double the time for the traces? Good question. Can you share the benchmark's code? Also, make sure frequency scaling is disabled on your system; it could explain these kinds of variations. J?r?mie > > Wolfgang R. > > > > _______________________________________________ > lttng-dev mailing list > lttng-dev at lists.lttng.org > http://lists.lttng.org/cgi-bin/mailman/listinfo/lttng-dev -- J?r?mie Galarneau EfficiOS Inc. http://www.efficios.com