From owner-freebsd-arch@FreeBSD.ORG Fri Mar 6 21:37:05 2015 Return-Path: Delivered-To: freebsd-arch@freebsd.org Received: from mx1.freebsd.org (mx1.freebsd.org [8.8.178.115]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by hub.freebsd.org (Postfix) with ESMTPS id C2AF3ED1; Fri, 6 Mar 2015 21:37:05 +0000 (UTC) Received: from mail-ie0-x22f.google.com (mail-ie0-x22f.google.com [IPv6:2607:f8b0:4001:c03::22f]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (Client CN "smtp.gmail.com", Issuer "Google Internet Authority G2" (verified OK)) by mx1.freebsd.org (Postfix) with ESMTPS id 8858A77C; Fri, 6 Mar 2015 21:37:05 +0000 (UTC) Received: by iecvy18 with SMTP id vy18so24966258iec.1; Fri, 06 Mar 2015 13:37:05 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20120113; h=mime-version:sender:in-reply-to:references:date:message-id:subject :from:to:cc:content-type; bh=42GlYp3kKhD1sL5Dpo6bs0MAuSHvyjOIt3zFER71bqI=; b=I8ln/4eRbp3pNZBNwAOfN/SmjEh7j3pPmcDuThyS+Z4iSqqcebGmYf5UI87Ec5eq0h yR3p1eiwINi+u8UacPrwdaM3YebJXizwdPjMK0cx+F0SdEHdiyhAyhBDPaq8feqcAAx3 fIkny4qWrb5lMRFOYvI+k8AY4t/BlV1iUrVnw2xGYALfMYAOM7pmP4DzSmfO1jijhT/K Gx+z25LZmcHh8u5MCivZR1JhFEsnxe6ZkyZFickg/cdEgm3TR10j1+uZaN2FT63w2QBE QX8L5XEzldy7b0xzBH69h/kgEzJwNYsYBCnIcXl25OLfRld/QIZW53UXOROfyxN03uhA FCQQ== MIME-Version: 1.0 X-Received: by 10.50.43.201 with SMTP id y9mr30609618igl.6.1425677824970; Fri, 06 Mar 2015 13:37:04 -0800 (PST) Sender: adrian.chadd@gmail.com Received: by 10.36.17.66 with HTTP; Fri, 6 Mar 2015 13:37:04 -0800 (PST) In-Reply-To: <1640664.8z9mx3EOQs@ralph.baldwin.cx> References: <1640664.8z9mx3EOQs@ralph.baldwin.cx> Date: Fri, 6 Mar 2015 13:37:04 -0800 X-Google-Sender-Auth: IHAsQkgKQM-8D-ylGP2jjswoX8s Message-ID: Subject: Re: RFC: Simplfying hyperthreading distinctions From: Adrian Chadd To: John Baldwin Content-Type: text/plain; charset=UTF-8 Cc: Andriy Gapon , "freebsd-arch@freebsd.org" X-BeenThere: freebsd-arch@freebsd.org X-Mailman-Version: 2.1.18-1 Precedence: list List-Id: Discussion related to FreeBSD architecture List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Fri, 06 Mar 2015 21:37:05 -0000 Hi! 1) I'd rather we leave them as SMT/HTT as they're slightly different things. Who knows if intel will re-introduce this stuff in their more embedded CPU line at a future time, or add another threading type in the future. Being told about the distinction is nice. 2) I'd rather we had it more clearly defind - machdep.htt_allowed / machdep.smt_allowed . Again, I'd rather have the distinction in case Intel decide again to make their embedded things use old-style threading. (The intel edison/galilleo boards use P1 style cores that are low power, I can imagine a world where they reuse HTT for that.) 3) I'd like that kind of tunable setting. And: 4) Yes, I'd also like a machdep tunable for "don't bother routing interrupts to SMT / HTTs". You have that patch in your jhbbsd tree; I don't think it's in HEAD yet? -adrian