From mboxrd@z Thu Jan 1 00:00:00 1970 From: David Mosberger Date: Fri, 10 Aug 2001 15:34:26 +0000 Subject: Re: [Linux-ia64] ping(8) faster than light (do_get_fast_time) (fwd) Message-Id: List-Id: References: In-Reply-To: MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit To: linux-ia64@vger.kernel.org >>>>> On Fri, 10 Aug 2001 15:15:56 +0200 (CEST), Martin Wilck said: Martin> The deeper reason is that on IA64, *do_get_fast_time() Martin> equals do_normal_gettime(), which simply returns xtime. This distinction doesn't make sense on ia64 because there is no (slow) gettimeofday() to begin with. Martin> 1) Is do_gettimeofday () too slow on IA64 to use it for Martin> do_get_fast_time() ? I have no idea what you mean here. On ia64 do_gettimeofday() returns xtime plus an itc based time offset. The kernel is careful to return only monotonically increasing time values, even in cases where the ITCs in different CPUs are not perfectly synchronized. Martin> 3) If no, the ping(8) program on IA64 should IMO be changed Martin> to not use SO_TIMESTAMP (equivalent to "ping -U" with the Martin> RH7.1 ping). We should first find out what the real problem is. What timestamps are present at the time ping is complaining? If the earlier timestamp is bigger than the later one, there is a bug somewhere. If they're equal (unlikely, given that we do ITC-based interpolation), ping shouldn't complain. --david