From mboxrd@z Thu Jan 1 00:00:00 1970 Message-ID: <448FD5EC.4060109@domain.hid> Date: Wed, 14 Jun 2006 03:25:00 -0600 From: Jim Cromie MIME-Version: 1.0 Subject: Re: [Xenomai-core] ns vs. tsc as internal timer base References: <448E98A3.6080707@domain.hid> <448E9E8B.70809@domain.hid> <448EA7F7.5000802@domain.hid> <448EB038.8070802@domain.hid> <448EE593.7010809@domain.hid> <448EF022.1040901@domain.hid> <17550.61982.685449.470866@domain.hid> <448EFCC5.60308@domain.hid> In-Reply-To: <448EFCC5.60308@domain.hid> Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit List-Id: "Xenomai life and development \(bug reports, patches, discussions\)" List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: Philippe Gerum Cc: Jan Kiszka , xenomai-core Philippe Gerum wrote: > Gilles Chanteperdrix wrote: >> Philippe Gerum wrote: >> > Redone the check here on a Centrino 1.6Mhz, and still have roughly >> x20 > improvement (a bit better actually). I'm using Debian/sarge >> gcc 3.3.5. >> >> I think I remember that Pentium M has a much shorter mull instruction >> than other processors of the family. >> > > That would explain. Anyway, as John Stulz put it: > "math is hard, lets go shopping!" > Heh. Appropriate that his name (Stultz) comes up here, as his generic-time (GTOD) patchset looks headed for 2.6.18, bringing with it a full re-working of linux timers / timeofday. IN this new world, time is kept on free-running counters. Ive been running this patchset on my soekris for some time, since GTOD detects that the TSC counts slowly, calls it insane, and does timing with the PIT. With GTOD, writing a new clocksource driver is easy, enough so I could do it. My clocksource patch uses the 27 mhz timer on the Geode CPU. Once the TSC is de-rated, mine becomes the best clocksource, and GTOD switches to it. All of which is to say .. new mainline code is coming, should this current rework notion wait, given that its will all need revisited again later