From mboxrd@z Thu Jan 1 00:00:00 1970 From: chetan loke Subject: Re: [PATCH net V4 2/2] igb: offer a PTP Hardware Clock instead of the timecompare method Date: Wed, 21 Mar 2012 17:50:34 -0400 Message-ID: References: <20120316065537.GB2199@netboy.at.omicron.at> <20120321170003.GA5533@netboy.at.omicron.at> <02874ECE860811409154E81DA85FBB580DA6E3@ORSMSX105.amr.corp.intel.com> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Cc: "e1000-devel@lists.sourceforge.net" , "netdev@vger.kernel.org" , "Ronciak, John" , "john.stultz@linaro.org" , "tglx@linutronix.de" To: "Keller, Jacob E" Return-path: In-Reply-To: <02874ECE860811409154E81DA85FBB580DA6E3@ORSMSX105.amr.corp.intel.com> List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: e1000-devel-bounces@lists.sourceforge.net List-Id: netdev.vger.kernel.org On Wed, Mar 21, 2012 at 1:09 PM, Keller, Jacob E wrote: >> -----Original Message----- >> From: Richard Cochran [mailto:richardcochran@gmail.com] >> Sent: Wednesday, March 21, 2012 10:00 AM >> To: chetan loke >> Cc: netdev@vger.kernel.org; e1000-devel@lists.sourceforge.net; Keller, Jacob >> E; Kirsher, Jeffrey T; Ronciak, John; john.stultz@linaro.org; >> tglx@linutronix.de >> Subject: Re: [PATCH net V4 2/2] igb: offer a PTP Hardware Clock instead of the >> timecompare method >> >> Can you please explain how using a seqlock could help here? >> >> Thanks, >> Richard > > My understanding of the seqlock, is that it prevents starvation of the hwtstamp calls in the rx and tx routines if/when a user hammers the gettime ioctl due to bad software design where 100+ apps are wanting direct access to the PHC. > Richard - Intent is to make the readers(get_time) wait (or return last read value if the seq_counter tripped because you know that this value was recent) and let the tx/rx path continue. I haven't looked in more details but as Jake mentioned you will also need to change the way you read the values(by not using timecounter_read in get_time). thanks Chetan ------------------------------------------------------------------------------ This SF email is sponsosred by: Try Windows Azure free for 90 days Click Here http://p.sf.net/sfu/sfd2d-msazure _______________________________________________ E1000-devel mailing list E1000-devel@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/e1000-devel To learn more about Intel® Ethernet, visit http://communities.intel.com/community/wired