From owner-freebsd-questions@FreeBSD.ORG Tue Sep 20 20:46:58 2011 Return-Path: Delivered-To: freebsd-questions@freebsd.org Received: from mx1.freebsd.org (mx1.freebsd.org [IPv6:2001:4f8:fff6::34]) by hub.freebsd.org (Postfix) with ESMTP id D3CC7106566B for ; Tue, 20 Sep 2011 20:46:58 +0000 (UTC) (envelope-from jusher71@yahoo.com) Received: from nm24-vm4.bullet.mail.ne1.yahoo.com (nm24-vm4.bullet.mail.ne1.yahoo.com [98.138.91.184]) by mx1.freebsd.org (Postfix) with SMTP id 95DA48FC0C for ; Tue, 20 Sep 2011 20:46:58 +0000 (UTC) Received: from [98.138.90.51] by nm24.bullet.mail.ne1.yahoo.com with NNFMP; 20 Sep 2011 20:34:42 -0000 Received: from [98.138.89.175] by tm4.bullet.mail.ne1.yahoo.com with NNFMP; 20 Sep 2011 20:34:42 -0000 Received: from [127.0.0.1] by omp1031.mail.ne1.yahoo.com with NNFMP; 20 Sep 2011 20:34:42 -0000 X-Yahoo-Newman-Property: ymail-3 X-Yahoo-Newman-Id: 815755.21781.bm@omp1031.mail.ne1.yahoo.com Received: (qmail 17932 invoked by uid 60001); 20 Sep 2011 20:34:42 -0000 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=yahoo.com; s=s1024; t=1316550882; bh=v9KePrYHUvRBH0SrWsuhQQlRYMYfSyB123vSZambs7Y=; h=X-YMail-OSG:Received:X-Mailer:Message-ID:Date:From:Subject:To:MIME-Version:Content-Type; b=DmWqsfJs4YMjSa8jbP8G9D2He6fSwQFEEjkFsYkmuOKeke1W7O3IiZfztvF+mqzsHKB5GJl0h5kCIH/StZfETYGDtjqDwGl36R3S/dpDa11lVDagR/JheHzLwzTSk8yJ0MAvAgJ9EqCfwcNRNy3ZW6G2VCFQHr5G1WG2E0A962k= DomainKey-Signature: a=rsa-sha1; q=dns; c=nofws; s=s1024; d=yahoo.com; h=X-YMail-OSG:Received:X-Mailer:Message-ID:Date:From:Subject:To:MIME-Version:Content-Type; b=OI2m+FdsvSHCGEsF6JNERAPPPkJ9lW14mUWT/FJfN01/4l7gRS8Dp8ytlh7/o0vCM74U6AtWDcwCKoYxKKFAYp4Ebi908bGJaUSnEmD1squOFGpqVmzk7SlFZqp1dZv3LjDxnwK06hSWZJz+QrBWuKtsljbs+AY3KMg1nTvL95U=; X-YMail-OSG: D_l0KXwVM1nz7AqCZ6y_DbyqBWN0Am6bI7TT.43JvAs8qcH tPioq9xX7B9amiUL5zpYrOmp8zEvmSFwwz4ClJjqEUHZHMUacMZGcKVFkR90 OCK_zFe6PQiBSAFRRHmlqHDPVIGgilcslkxLHXK1rcogP1ofSX8jCsAJlbgZ PHlb4n1qg9gAB6gB4tq6XJhnDnVA6d.5yORWeYewnUsn2lOL4GSDZN2Msy2E 13HT_KTMxrRCEJ5VJXupEWS3kk.reJu.p35DwcesuiHqlZbzJ_bo6hmx_FU5 Ren2ytkEswOUZWx4d3PK7kdKOPB.Pj7PO6LugEDmk06shPdkDaMGr6rjbbyL HCMNATAFC0ArL10q5NM73WBpPkRhLILygEU1S6fIFvQ-- Received: from [173.254.192.37] by web121217.mail.ne1.yahoo.com via HTTP; Tue, 20 Sep 2011 13:34:42 PDT X-Mailer: YahooMailClassic/14.0.5 YahooMailWebService/0.8.114.317681 Message-ID: <1316550882.13474.YahooMailClassic@web121217.mail.ne1.yahoo.com> Date: Tue, 20 Sep 2011 13:34:42 -0700 (PDT) From: Jason Usher To: freebsd-questions@freebsd.org MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Subject: How can I disable hyperthreads, but NOT smp ? X-BeenThere: freebsd-questions@freebsd.org X-Mailman-Version: 2.1.5 Precedence: list List-Id: User questions List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Tue, 20 Sep 2011 20:46:58 -0000 FreeBSD 6.4-RELEASE system with two physical CPUs, each of which are HT capable. From dmesg: cpu0 (BSP): APIC ID: 0 cpu1 (AP): APIC ID: 1 cpu2 (AP): APIC ID: 6 cpu3 (AP): APIC ID: 7 I also see this: machdep.hyperthreading_allowed: 0 The problem is, I have reason to believe that my workload benefits greatly from SMP, but is not playing nicely with hyperthreading. That is, it is trying to farm out 4 things at a time to a cpu setup that really is only able to do two things at a time. How can I disable HT completely, but still retain ALL the benefits of SMP ? Thanks.