From mboxrd@z Thu Jan 1 00:00:00 1970 From: Dmitry Vyal Subject: Re: Recommended method of getting timestamps? Date: Fri, 06 Sep 2013 10:33:58 +0400 Message-ID: <52297756.7060308@gmail.com> References: <16BB02EF-879C-4DB1-804E-E5E6E08B935E@mahan.org> Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Cc: dev-VfR2kkLFssw@public.gmane.org To: Patrick Mahan Return-path: In-Reply-To: <16BB02EF-879C-4DB1-804E-E5E6E08B935E-5dHXHCkEAVbYtjvyW6yDsg@public.gmane.org> List-Id: patches and discussions about DPDK List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: dev-bounces-VfR2kkLFssw@public.gmane.org Sender: "dev" Hello Patrick, I guess gettimeofday is too heavy if all you need is an abstract timestamp not related to any particular calendar. I think you should look at rte_rdtsc()? It returns a current value of CPU tick counter. So it's very cheap (just a few clocks) and has a great resolution (a fraction of nanosecond). Regards, Dmitry > I have a need to keep a timestamp on a piece of global data. When then timestamp grows too old I want to refresh that data. Is it safe to use, gettimeofday()? > > I thought about using an alarm, but I need to set an alarm from inside the alarm callback which doesn't look like it will work due to the spinlock on the alarm list. > > And since this is inside the driver I am working on, setting up a timer is not simple. > > So, I figure to timestamp the data, wait until I need to access it, check the timestamp and refresh if it is too old. > > Thoughts? Suggestions? > > Thanks, > > Patrick > > Coming to you from deep inside Fortress Mahan