From owner-svn-src-all@freebsd.org Sat Mar 19 03:22:22 2016 Return-Path: Delivered-To: svn-src-all@mailman.ysv.freebsd.org Received: from mx1.freebsd.org (mx1.freebsd.org [IPv6:2001:1900:2254:206a::19:1]) by mailman.ysv.freebsd.org (Postfix) with ESMTP id 5DBF2AD4429; Sat, 19 Mar 2016 03:22:22 +0000 (UTC) (envelope-from kostikbel@gmail.com) Received: from kib.kiev.ua (kib.kiev.ua [IPv6:2001:470:d5e7:1::1]) (using TLSv1 with cipher DHE-RSA-CAMELLIA256-SHA (256/256 bits)) (Client did not present a certificate) by mx1.freebsd.org (Postfix) with ESMTPS id EA7F6EC4; Sat, 19 Mar 2016 03:22:21 +0000 (UTC) (envelope-from kostikbel@gmail.com) Received: from tom.home (kostik@localhost [127.0.0.1]) by kib.kiev.ua (8.15.2/8.15.2) with ESMTPS id u2J3MGFR046974 (version=TLSv1 cipher=DHE-RSA-CAMELLIA256-SHA bits=256 verify=NO); Sat, 19 Mar 2016 05:22:17 +0200 (EET) (envelope-from kostikbel@gmail.com) DKIM-Filter: OpenDKIM Filter v2.10.3 kib.kiev.ua u2J3MGFR046974 Received: (from kostik@localhost) by tom.home (8.15.2/8.15.2/Submit) id u2J3MG1D046973; Sat, 19 Mar 2016 05:22:16 +0200 (EET) (envelope-from kostikbel@gmail.com) X-Authentication-Warning: tom.home: kostik set sender to kostikbel@gmail.com using -f Date: Sat, 19 Mar 2016 05:22:16 +0200 From: Konstantin Belousov To: John Baldwin Cc: src-committers@freebsd.org, svn-src-all@freebsd.org, svn-src-head@freebsd.org Subject: Re: svn commit: r297039 - head/sys/x86/x86 Message-ID: <20160319032216.GZ1741@kib.kiev.ua> References: <201603181948.u2IJmndg063765@repo.freebsd.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <201603181948.u2IJmndg063765@repo.freebsd.org> User-Agent: Mutt/1.5.24 (2015-08-30) X-Spam-Status: No, score=-2.0 required=5.0 tests=ALL_TRUSTED,BAYES_00, DKIM_ADSP_CUSTOM_MED,FREEMAIL_FROM,NML_ADSP_CUSTOM_MED autolearn=no autolearn_force=no version=3.4.1 X-Spam-Checker-Version: SpamAssassin 3.4.1 (2015-04-28) on tom.home X-BeenThere: svn-src-all@freebsd.org X-Mailman-Version: 2.1.21 Precedence: list List-Id: "SVN commit messages for the entire src tree \(except for " user" and " projects" \)" List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Sat, 19 Mar 2016 03:22:22 -0000 On Fri, Mar 18, 2016 at 07:48:49PM +0000, John Baldwin wrote: > > - for (x = 0; x < delay; x += 5) { > + for (x = 0; x < delay; x++) { > if ((lapic_read_icr_lo() & APIC_DELSTAT_MASK) == > APIC_DELSTAT_IDLE) > return (1); > - DELAY(5); > + DELAY(1); > } > return (0); > } Ideally we would structure the loop differently. I think it is more efficient WRT latency to only block execution by ia32_pause(), and compare the the getbinuptime() results to calculate spent time, on each loop step.