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d=linutronix.de; s=2020e; t=1606166724; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: in-reply-to:in-reply-to:references:references; bh=cTdlVvBzV3X2SG+m6YMVXF6nkX8krtH6dkjkxUwZQiI=; b=Jy9SH6vPX9Nh5MsIwQRQ0leykfm4dF6xZwKpAQHhnLTyqfYcQIdSc2a1e/yCvwOGRDF7SZ GwO0NwtwLoui1cDg== To: Andy Lutomirski , Peter Zijlstra Cc: Linus Torvalds , Mel Gorman , LKML , the arch/x86 maintainers , Christoph Hellwig , Matthew Wilcox , Daniel Vetter , Andrew Morton , Linux-MM , Ingo Molnar , Juri Lelli , Vincent Guittot , Dietmar Eggemann , Steven Rostedt , Ben Segall , Daniel Bristot de Oliveira Subject: Re: [patch V4 4/8] sched: Make migrate_disable/enable() independent of RT In-Reply-To: <87mtz7n5ae.fsf@nanos.tec.linutronix.de> References: <20201118194838.753436396@linutronix.de> <20201118204007.269943012@linutronix.de> <20201119093834.GH3306@suse.de> <20201119111411.GL3121378@hirez.programming.kicks-ass.net> <20201119182843.GA2414@hirez.programming.kicks-ass.net> <87tutkolq1.fsf@nanos.tec.linutronix.de> <20201120092928.GA3021@hirez.programming.kicks-ass.net> <87mtz7n5ae.fsf@nanos.tec.linutronix.de> Date: Mon, 23 Nov 2020 22:25:24 +0100 Message-ID: <87h7pfn4u3.fsf@nanos.tec.linutronix.de> MIME-Version: 1.0 Content-Type: text/plain X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: On Mon, Nov 23 2020 at 22:15, Thomas Gleixner wrote: > On Sun, Nov 22 2020 at 15:16, Andy Lutomirski wrote: >> On Fri, Nov 20, 2020 at 1:29 AM Peter Zijlstra wrote: >> The common case of a CPU switching back and forth between a small >> number of mms would have no significant overhead. > > For CPUs which do not support PCID this sucks, which is everything pre > Westmere and all of 32bit. Yes, 32bit. If we go there then 32bit has to > bite the bullet and use the very same mechanism. Not that I care much > TBH. Bah, I completely forgot that AMD does not support PCID before Zen3 which is a major showstopper. Thanks, tglx