From mboxrd@z Thu Jan 1 00:00:00 1970 From: Anton Ivanov Subject: Re: Arches that don't support PREEMPT Date: Tue, 19 Sep 2023 17:41:21 +0100 Message-ID: References: <87zg1u1h5t.fsf@oracle.com> <87led2wdj0.ffs@tglx> <0e69f7df80dc5878071deb0d80938138d19de1d1.camel@physik.fu-berlin.de> <20230919134218.GA39281@noisy.programming.kicks-ass.net> <87y1h2ur98.ffs@tglx> <9a5c0856-d542-9912-7494-53d7fe4538a3@cambridgegreys.com> <551475267.58816.1695140566849.JavaMail.zimbra@nod.at> Mime-Version: 1.0 Content-Transfer-Encoding: quoted-printable Return-path: Content-Language: en-US In-Reply-To: <551475267.58816.1695140566849.JavaMail.zimbra@nod.at> List-ID: Content-Type: text/plain; charset="iso-8859-1"; format="flowed" To: Richard Weinberger Cc: tglx , Peter Zijlstra , John Paul Adrian Glaubitz , Matthew Wilcox , torvalds , Ankur Arora , linux-kernel , linux-mm , x86 , Andrew Morton , Andy Lutomirski , bp , dave hansen , hpa , mingo , juri lelli , vincent guittot , mgorman@suse.de, Steven Rostedt , jon grimm , bharata@amd.com, raghavendra kt , boris ostrovsky On 19/09/2023 17:22, Richard Weinberger wrote: > ----- Urspr=C3=BCngliche Mail ----- >> Von: "anton ivanov" >> It's been a while. I remember that I dropped it at the time, but do not = remember >> the full details. >> >> There was some stuff related to FP state and a few other issues I ran in= to while >> rewriting the interrupt controller. Some of it may be resolved by now as= we are >> using host cpu flags, etc. >=20 > I remember also having a hacky but working version almost 10 years ago. > It was horrible slow because of the extra scheduler rounds. > But yes, if PREEMPT will be a must-have feature we'll have to try again. We will need proper fpu primitives for starters that's for sure. fpu_star/e= nd in UML are presently NOOP. Some of the default spinlocks and other stuff which we pick up from generic= may need to change as well. This is off the top of my head and something which we can fix straight away= . I will send some patches to the mailing list tomorrow or on Thu. A. >=20 > Thanks, > //richard >=20 > _______________________________________________ > linux-um mailing list > linux-um@lists.infradead.org > http://lists.infradead.org/mailman/listinfo/linux-um --=20 Anton R. Ivanov Cambridgegreys Limited. Registered in England. Company Number 10273661 https://www.cambridgegreys.com/