From mboxrd@z Thu Jan 1 00:00:00 1970 From: Thomas Monjalon Subject: Re: Sporadic errors while initializing NICs in example applications, dpdk-1.5.0r1 Date: Fri, 29 Nov 2013 10:20:58 -0800 (PST) Message-ID: <4967601.BLy1PQ6cQ3@x220> References: <528F4E41.2000405@gmail.com> <52987236.3020707@gmail.com> <3439195.NJQbpGS54N@x220> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7Bit Cc: "dev-VfR2kkLFssw@public.gmane.org" To: Dmitry Vyal Return-path: In-Reply-To: <3439195.NJQbpGS54N@x220> 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" Thomas29/11/2013 13:25, Monjalon : > 29/11/2013 14:53, Dmitry Vyal : > > On 11/28/2013 03:01 PM, Richardson, Bruce wrote: > > > [BR] Frequency changes should not affect timers for modern Intel CPUs. > > > > The error frequency greatly reduces if I patch > > loop limit as I described earlier or if I call rte_power_init and > > rte_power_freq_max as Thomas suggested. > > > > But the only way to get rid of them completely is to set performance > > governor. > > Please check that your hardware do not support invariant TSC. > It would explain why you need to fix frequency. > > I attach a simple code to test CPU feature "Invariant TSC". Note that this feature is called constant_tsc in /proc/cpuinfo: grep --color -m1 constant_tsc /proc/cpuinfo It is checked by check_tsc_flags() at DPDK initialization and should print a warning if missing: http://dpdk.org/browse/dpdk/commit/?id=e7c8996e13b9abb706ea0de53271346f4f86ca03 -- Thomas