From patchwork Sat Nov 18 00:11:31 2017 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Martin Wilck X-Patchwork-Id: 10064227 X-Patchwork-Delegate: christophe.varoqui@free.fr Return-Path: Received: from mail.wl.linuxfoundation.org (pdx-wl-mail.web.codeaurora.org [172.30.200.125]) by pdx-korg-patchwork.web.codeaurora.org (Postfix) with ESMTP id 0B9F760352 for ; Sat, 18 Nov 2017 00:12:56 +0000 (UTC) Received: from mail.wl.linuxfoundation.org (localhost [127.0.0.1]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id F24272AE48 for ; Sat, 18 Nov 2017 00:12:55 +0000 (UTC) Received: by mail.wl.linuxfoundation.org (Postfix, from userid 486) id E723A2AE4D; Sat, 18 Nov 2017 00:12:55 +0000 (UTC) X-Spam-Checker-Version: SpamAssassin 3.3.1 (2010-03-16) on pdx-wl-mail.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-6.9 required=2.0 tests=BAYES_00,RCVD_IN_DNSWL_HI autolearn=ham version=3.3.1 Received: from mx1.redhat.com (mx1.redhat.com [209.132.183.28]) (using TLSv1.2 with cipher DHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.wl.linuxfoundation.org (Postfix) with ESMTPS id 7A28F2AE48 for ; Sat, 18 Nov 2017 00:12:55 +0000 (UTC) Received: from smtp.corp.redhat.com (int-mx06.intmail.prod.int.phx2.redhat.com [10.5.11.16]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mx1.redhat.com (Postfix) with ESMTPS id 7F8A583F46; Sat, 18 Nov 2017 00:12:54 +0000 (UTC) Received: from colo-mx.corp.redhat.com (colo-mx02.intmail.prod.int.phx2.redhat.com [10.5.11.21]) by smtp.corp.redhat.com (Postfix) with ESMTPS id 61DC15C3FD; Sat, 18 Nov 2017 00:12:54 +0000 (UTC) Received: from lists01.pubmisc.prod.ext.phx2.redhat.com (lists01.pubmisc.prod.ext.phx2.redhat.com [10.5.19.33]) by colo-mx.corp.redhat.com (Postfix) with ESMTP id 3D48C4A467; Sat, 18 Nov 2017 00:12:54 +0000 (UTC) Received: from smtp.corp.redhat.com (int-mx06.intmail.prod.int.phx2.redhat.com [10.5.11.16]) by lists01.pubmisc.prod.ext.phx2.redhat.com (8.13.8/8.13.8) with ESMTP id vAI0CcSZ011841 for ; Fri, 17 Nov 2017 19:12:38 -0500 Received: by smtp.corp.redhat.com (Postfix) id 061325C545; Sat, 18 Nov 2017 00:12:38 +0000 (UTC) Delivered-To: dm-devel@redhat.com Received: from mx1.redhat.com (ext-mx08.extmail.prod.ext.phx2.redhat.com [10.5.110.32]) by smtp.corp.redhat.com (Postfix) with ESMTPS id F3F475C1A1 for ; Sat, 18 Nov 2017 00:12:35 +0000 (UTC) Received: from smtp.nue.novell.com (smtp.nue.novell.com [195.135.221.5]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mx1.redhat.com (Postfix) with ESMTPS id 8598EC0587C0 for ; Sat, 18 Nov 2017 00:12:34 +0000 (UTC) Received: from emea4-mta.ukb.novell.com ([10.120.13.87]) by smtp.nue.novell.com with ESMTP (TLS encrypted); Sat, 18 Nov 2017 01:12:32 +0100 Received: from apollon.suse.de.de (nwb-a10-snat.microfocus.com [10.120.13.201]) by emea4-mta.ukb.novell.com with ESMTP (TLS encrypted); Sat, 18 Nov 2017 00:12:04 +0000 From: Martin Wilck To: Christophe Varoqui , Guan Junxiong Date: Sat, 18 Nov 2017 01:11:31 +0100 Message-Id: <20171118001134.26622-2-mwilck@suse.com> In-Reply-To: <20171118001134.26622-1-mwilck@suse.com> References: <20171118001134.26622-1-mwilck@suse.com> X-Greylist: Sender passed SPF test, Sender IP whitelisted by DNSRBL, ACL 207 matched, not delayed by milter-greylist-4.5.16 (mx1.redhat.com [10.5.110.32]); Sat, 18 Nov 2017 00:12:35 +0000 (UTC) X-Greylist: inspected by milter-greylist-4.5.16 (mx1.redhat.com [10.5.110.32]); Sat, 18 Nov 2017 00:12:35 +0000 (UTC) for IP:'195.135.221.5' DOMAIN:'smtp.nue.novell.com' HELO:'smtp.nue.novell.com' FROM:'mwilck@suse.com' RCPT:'' X-RedHat-Spam-Score: -2.301 (RCVD_IN_DNSWL_MED, SPF_PASS) 195.135.221.5 smtp.nue.novell.com 195.135.221.5 smtp.nue.novell.com X-Scanned-By: MIMEDefang 2.78 on 10.5.110.32 X-Scanned-By: MIMEDefang 2.79 on 10.5.11.16 X-loop: dm-devel@redhat.com Cc: dm-devel@redhat.com Subject: [dm-devel] [PATCH 1/4] libmultipath: path latency: fix default base num X-BeenThere: dm-devel@redhat.com X-Mailman-Version: 2.1.12 Precedence: junk List-Id: device-mapper development List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , MIME-Version: 1.0 Sender: dm-devel-bounces@redhat.com Errors-To: dm-devel-bounces@redhat.com X-Scanned-By: MIMEDefang 2.79 on 10.5.11.16 X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-4.5.16 (mx1.redhat.com [10.5.110.27]); Sat, 18 Nov 2017 00:12:54 +0000 (UTC) X-Virus-Scanned: ClamAV using ClamSMTP I don't think anyone can measure latency to 1% accuracy. It's better to not even pretend to be able to. 10% should be fine even for the most latency-critical environments. Signed-off-by: Martin Wilck Reviewed-by: Guan Junxiong --- libmultipath/prioritizers/path_latency.c | 5 +++-- 1 file changed, 3 insertions(+), 2 deletions(-) diff --git a/libmultipath/prioritizers/path_latency.c b/libmultipath/prioritizers/path_latency.c index 9d5397ec1b3a..b8c5bc7c50a4 100644 --- a/libmultipath/prioritizers/path_latency.c +++ b/libmultipath/prioritizers/path_latency.c @@ -42,8 +42,9 @@ #define DEF_IO_NUM 100 #define MAX_BASE_NUM 10 -#define MIN_BASE_NUM 1.01 -#define DEF_BASE_NUM 1.5 +#define MIN_BASE_NUM 1.1 +// This is 10**(1/4). 4 prio steps correspond to a factor of 10. +#define DEF_BASE_NUM 1.77827941004 #define MAX_AVG_LATENCY 100000000. /* Unit: us */ #define MIN_AVG_LATENCY 1. /* Unit: us */