From owner-freebsd-questions@FreeBSD.ORG Mon Dec 8 09:43:07 2014 Return-Path: Delivered-To: freebsd-questions@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 13D321B9; Mon, 8 Dec 2014 09:43:07 +0000 (UTC) Received: from mail-wg0-x229.google.com (mail-wg0-x229.google.com [IPv6:2a00:1450:400c:c00::229]) (using TLSv1 with cipher ECDHE-RSA-RC4-SHA (128/128 bits)) (Client CN "smtp.gmail.com", Issuer "Google Internet Authority G2" (verified OK)) by mx1.freebsd.org (Postfix) with ESMTPS id B1EB87A9; Mon, 8 Dec 2014 09:43:06 +0000 (UTC) Received: by mail-wg0-f41.google.com with SMTP id y19so5743656wgg.0 for ; Mon, 08 Dec 2014 01:43:05 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20120113; h=mime-version:date:message-id:subject:from:to:cc:content-type; bh=jtfu6pSC2KlrzcqpzWEScy8RbVrsr4JSBaPM6VTsl7g=; b=c19ymOvfYVx6BhfFfUxpvs2AZAWxJ+4mscjENQt4PBzTWgafyBGvwI5wKgP+mBDHeQ 2NF6hFeg118zuUSnxVRiDwVwV+NWhI+vl5wpcjRNXftTyufAqheF/EzNnofuuuce0xsm 9CVaLOJhnVsrmG1p95KksP5yvjr/YG8WZ3tAodL/cLk+CW3TIAjVS27o7jFtV9zsMuUj wIDw0jYLa6t/dyvCd1jzAFhpPLL28EcCAFIo9yW4K8Qew9CpVT+3VXp9wM/ebWqT7J1P rg6fL9VLSwQfVD4n/Yw3+i2eN4Tx6GyE46qaHiO0lG4K4idQz4lb0FLk3qzbSmboPf9c tk3Q== MIME-Version: 1.0 X-Received: by 10.180.74.68 with SMTP id r4mr22073776wiv.33.1418031785120; Mon, 08 Dec 2014 01:43:05 -0800 (PST) Received: by 10.216.151.130 with HTTP; Mon, 8 Dec 2014 01:43:05 -0800 (PST) Date: Mon, 8 Dec 2014 04:43:05 -0500 Message-ID: Subject: HyperThreading on Intel Xeon Haswell, a benefit? From: grarpamp To: freebsd-hardware@freebsd.org Content-Type: text/plain; charset=UTF-8 Cc: freebsd-performance@freebsd.org, freebsd-smp@freebsd.org, freebsd-questions@freebsd.org X-BeenThere: freebsd-questions@freebsd.org X-Mailman-Version: 2.1.18-1 Precedence: list List-Id: User questions List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Mon, 08 Dec 2014 09:43:07 -0000 HyperThreading on Intel Xeon Haswell, a benefit? What bits of FreeBSD are aware and can take proper advantage of Intel HTT, such as its thread/process schedulers (sched-BSD/ULE/...), etc? What system/app loads are, or are not, likely to benefit with today's HyperThreading CPU's? Kernel (ZFS/crypto/net/...) vs. Userland (apps)? Does anyone have performance stats for this current class of CPU to post comparing HT (enabled and disabled) while using more than four processes/threads in parallel? For instance, these two Intel Xeon Haswell four core CPU's are identical except for HT [1] (e3-1226v3 and e3-1246v3), and you can always turn HT off for testing. http://ark.intel.com/compare/80917,80916 There are some Core i3/i5/i7 Haswell parts with HT as well. http://ark.intel.com/Search/Advanced?s=t&ECCMemory=true&VTD=true&AESTech=true There don't seem to be many reviews of Xeon processors, let alone HT. And most Unix talk of HT seems dated by at least a few years and a couple processor generations. Also, was the HT cache leak security issue from a decade ago ever fixed in hardware? "Cache missing for fun and profit" http://www.daemonology.net/papers/ Being unsure of the best list, please direct replies to whichever is good. Thanks. [1] Plus 200MHz/6% clock per core and $59/27% market price bumps, but this thread is about whether or not there is any benefit to HT in current Intel CPU's such as Haswell, how much of one, and where. Once that is determined, then you can factor in other parameters like these to see if it's an overall value.