From owner-freebsd-questions@FreeBSD.ORG Thu Apr 5 15:41:52 2007 Return-Path: X-Original-To: freebsd-questions@freebsd.org Delivered-To: freebsd-questions@freebsd.org Received: from mx1.freebsd.org (mx1.freebsd.org [69.147.83.52]) by hub.freebsd.org (Postfix) with ESMTP id 9827316A54C for ; Thu, 5 Apr 2007 15:41:52 +0000 (UTC) (envelope-from kline@tao.thought.org) Received: from tao.thought.org (dsl231-043-140.sea1.dsl.speakeasy.net [216.231.43.140]) by mx1.freebsd.org (Postfix) with ESMTP id 3895413C44B for ; Thu, 5 Apr 2007 15:41:52 +0000 (UTC) (envelope-from kline@tao.thought.org) Received: from tao.thought.org (localhost [127.0.0.1]) by tao.thought.org (8.13.8/8.13.1) with ESMTP id l35FgdbQ088476; Thu, 5 Apr 2007 08:42:39 -0700 (PDT) (envelope-from kline@tao.thought.org) Received: (from kline@localhost) by tao.thought.org (8.13.8/8.13.1/Submit) id l35FgcrM088475; Thu, 5 Apr 2007 08:42:38 -0700 (PDT) (envelope-from kline) Date: Thu, 5 Apr 2007 08:42:38 -0700 From: Gary Kline To: scuba@centroin.com.br Message-ID: <20070405154238.GB88189@thought.org> References: <20070405093721.N22331@trex.centroin.com.br> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20070405093721.N22331@trex.centroin.com.br> User-Agent: Mutt/1.4.2.2i X-Organization: Thought Unlimited. Public service Unix since 1986. X-Of_Interest: Observing twenty years of service to the Unix community Cc: freebsd-questions@freebsd.org Subject: Re: unroll-loops - Is it always safe? 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: Thu, 05 Apr 2007 15:41:52 -0000 On Thu, Apr 05, 2007 at 09:54:08AM -0300, scuba@centroin.com.br wrote: > Hi All, > > Is it always safe to use "-funroll-loops" as a flag to > /etc/make.conf ? Does it realy improve the compiled programs? > > When should I avoid to use it? If you are using gcc42 -funroll-loops can be a win. gcc3.x is less savvy about knowing the limits of complexity to unroll which loops. I'm doing some tests with gcc34 (default) and gcc42. The latter can yield significant improvements iff you know what you're doing. It's no magic bullet. gary > > - Marcelo > > _______________________________________________ > freebsd-questions@freebsd.org mailing list > http://lists.freebsd.org/mailman/listinfo/freebsd-questions > To unsubscribe, send any mail to "freebsd-questions-unsubscribe@freebsd.org" -- Gary Kline kline@thought.org www.thought.org Public Service Unix