From mboxrd@z Thu Jan 1 00:00:00 1970 Message-ID: <30117851.1185278735407.JavaMail.ngmail@domain.hid> Date: Tue, 24 Jul 2007 14:05:35 +0200 (CEST) From: "M. Koehrer" In-Reply-To: <1185202908.5998.271.camel@domain.hid> MIME-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: quoted-printable References: <1185202908.5998.271.camel@domain.hid> <16123805.1184916759093.JavaMail.ngmail@domain.hid> <1184890451.28303.356.camel@domain.hid> <1184852543.28303.67.camel@domain.hid> <24703926.1184851660664.JavaMail.ngmail@domain.hid> <32098568.1184853156077.JavaMail.ngmail@domain.hid> <25782679.1184932464850.JavaMail.ngmail@domain.hid> <1184933771.5998.3.camel@domain.hid> Subject: Re: [Xenomai-core] RPI is good for you List-Id: "Xenomai life and development \(bug reports, patches, discussions\)" List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: rpm@xenomai.org, mathias_koehrer@domain.hid Cc: jan.kiszka@domain.hid, xenomai@xenomai.org Hi Philippe, I have attached this patch to my application. So far it looks really good. However, I leave my test running to be sure that it works. Regards Mathias=20 > On Fri, 2007-07-20 at 14:16 +0200, Philippe Gerum wrote:=20 > > On Fri, 2007-07-20 at 13:54 +0200, M. Koehrer wrote: > > > Hi Philippe, > > > I left my test running for a couple of hours - no freeze so far...=20 > > >=20 > > > However, I have to do some other stuff on this machine, I have to sto= p > the test now... > > >=20 > >=20 > > Ok, thanks for the feedback. I will send an extended patch later today, > > so that you could test it on a longer period when you see fit. >=20 > It took me a bit longer than expected, but here is a patch which > addresses all the pending issues with RPI, hopefully (applies against > 2.3.1 stock). >=20 > The good thing about Jan grumbling at me, is that this usually makes me > look at the big picture anew. And the RPI picture was not that nice, > that's a fact. >=20 > Beside the locking sequence issue, the ex-aequo #1 problem was that CPU > migration of Linux tasks causing a RPI boost had some very nasty > side-effects on RPI management, and would create all sort of funky > situations I'm too shameful to talk about, except under the generic term > of "horrendous mess". >=20 > Now, regarding the deadlock issue, suppressing the RPI-specific locking > entirely would have been the best solution, but unfortunately, the > migration scheme makes this out of reach, at least without resorting to > some hairy and likely unreliable implementation. Therefore, the solution > I came with consists of making the RPI lock a per-cpu thing, so that > most RPI routines are actually grabbing a _local_ lock wrt the current > CPU, those routines being allowed hold the nklock as they wish. When > some per-CPU RPI lock is accessed from a remote CPU, it is guaranteed > that _no nklock_ may be held nested. Actually, the remote case only > occurs once, in rpi_clear_remote(), and all its callers are guaranteed > to be nklock-free (a debug assertion even enforces that). >=20 > For the migration issue, the RPI transitions have been ironed out to > make sure we deal properly with all the subtleties of the Linux load > balancer. >=20 > Mathias, please let me know if the attached patch improves the situation > on your side. >=20 > --=20 > Philippe. >=20 >=20 >=20 --=20 Mathias Koehrer mathias_koehrer@domain.hid Viel oder wenig? Schnell oder langsam? Unbegrenzt surfen + telefonieren ohne Zeit- und Volumenbegrenzung? DAS TOP ANGEBOT F=DCR ALLE NEUEINSTEIGER Jetzt bei Arcor: g=FCnstig und schnell mit DSL - das All-Inclusive-Paket f=FCr clevere Doppel-Sparer, nur 34,95 =80 inkl. DSL- und ISDN-Grundgeb= =FChr! http://www.arcor.de/rd/emf-dsl-2