From patchwork Sat Mar 4 15:33:29 2017 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Sven Eckelmann X-Patchwork-Id: 16968 X-Patchwork-Delegate: sw@simonwunderlich.de Return-Path: X-Original-To: patchwork@open-mesh.org Delivered-To: patchwork@open-mesh.org Received: from open-mesh.org (localhost [IPv6:::1]) by open-mesh.org (Postfix) with ESMTP id 3A64683609; Sat, 4 Mar 2017 16:33:36 +0100 (CET) Authentication-Results: open-mesh.org; dmarc=none header.from=narfation.org Authentication-Results: open-mesh.org; dkim=fail reason="verification failed; unprotected key" header.d=narfation.org header.i=@narfation.org header.b=WEgM7A6T; dkim-adsp=fail (unprotected policy); dkim-atps=neutral Received-SPF: Pass (sender SPF authorized) identity=mailfrom; client-ip=2001:4d88:2000:7::2; helo=v3-1039.vlinux.de; envelope-from=sven@narfation.org; receiver=b.a.t.m.a.n@lists.open-mesh.org Authentication-Results: open-mesh.org; dmarc=pass header.from=narfation.org Received: from v3-1039.vlinux.de (narfation.org [IPv6:2001:4d88:2000:7::2]) by open-mesh.org (Postfix) with ESMTPS id 2235D83606 for ; Sat, 4 Mar 2017 16:33:35 +0100 (CET) Received: from sven-desktop.home.narfation.org (p200300C593CD6FF90000000000002E16.dip0.t-ipconnect.de [IPv6:2003:c5:93cd:6ff9::2e16]) by v3-1039.vlinux.de (Postfix) with ESMTPSA id A22801100D8 for ; Sat, 4 Mar 2017 16:33:34 +0100 (CET) Authentication-Results: v3-1039.vlinux.de; dmarc=none header.from=narfation.org DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=narfation.org; s=20121; t=1488641614; bh=sCZej89es8k4vmtJFW6ANXE//4EklrdrB/zxcDAN/KU=; h=From:To:Subject:Date:In-Reply-To:References:From; b=WEgM7A6T0Y+y2kgt0plsBnOfeGHlJc1yTCGndAJT6WtmriF/ei5HJddiT8LfIThBA knzpQ8yuhm5A6YMiA8/PEvcpskxYma76Teqyf9opJ7F7SPjUqJ8Zowf7Fz8dyOGwmg NA8kGrVCPQtqpWgl2jpDNvHyzykURb0tVs35+Xms= From: Sven Eckelmann To: b.a.t.m.a.n@lists.open-mesh.org Date: Sat, 4 Mar 2017 16:33:29 +0100 Message-Id: <20170304153331.22420-1-sven@narfation.org> X-Mailer: git-send-email 2.11.0 In-Reply-To: <13175888.lmslI35NF1@sven-edge> References: <13175888.lmslI35NF1@sven-edge> Subject: [B.A.T.M.A.N.] [PATCH maint 1/3] batman-adv: average: change to declare precision, not factor X-BeenThere: b.a.t.m.a.n@lists.open-mesh.org X-Mailman-Version: 2.1.18 Precedence: list List-Id: The list for a Better Approach To Mobile Ad-hoc Networking List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Reply-To: The list for a Better Approach To Mobile Ad-hoc Networking Errors-To: b.a.t.m.a.n-bounces@lists.open-mesh.org Sender: "B.A.T.M.A.N" From: Johannes Berg Declaring the factor is counter-intuitive, and people are prone to using small(-ish) values even when that makes no sense. Change the DECLARE_EWMA() macro to take the fractional precision, in bits, rather than a factor, and update all users. While at it, add some more documentation. Acked-by: David S. Miller Signed-off-by: Johannes Berg [sven@narfation.org: Added compatibility code] Signed-off-by: Sven Eckelmann --- compat-include/linux/average.h | 67 +++++++++++++++++++++++++++--------------- net/batman-adv/types.h | 2 +- 2 files changed, 45 insertions(+), 24 deletions(-) diff --git a/compat-include/linux/average.h b/compat-include/linux/average.h index ec022cb6..a1e3c254 100644 --- a/compat-include/linux/average.h +++ b/compat-include/linux/average.h @@ -26,49 +26,70 @@ #include -#if LINUX_VERSION_CODE < KERNEL_VERSION(4, 3, 0) +#if LINUX_VERSION_CODE >= KERNEL_VERSION(4, 3, 0) +#undef DECLARE_EWMA +#endif /* < KERNEL_VERSION(4, 3, 0) */ -/* Exponentially weighted moving average (EWMA) */ +/* + * Exponentially weighted moving average (EWMA) + * + * This implements a fixed-precision EWMA algorithm, with both the + * precision and fall-off coefficient determined at compile-time + * and built into the generated helper funtions. + * + * The first argument to the macro is the name that will be used + * for the struct and helper functions. + * + * The second argument, the precision, expresses how many bits are + * used for the fractional part of the fixed-precision values. + * + * The third argument, the weight reciprocal, determines how the + * new values will be weighed vs. the old state, new values will + * get weight 1/weight_rcp and old values 1-1/weight_rcp. Note + * that this parameter must be a power of two for efficiency. + */ -#define DECLARE_EWMA(name, _factor, _weight) \ +#define DECLARE_EWMA(name, _precision, _weight_rcp) \ struct ewma_##name { \ unsigned long internal; \ }; \ static inline void ewma_##name##_init(struct ewma_##name *e) \ { \ - BUILD_BUG_ON(!__builtin_constant_p(_factor)); \ - BUILD_BUG_ON(!__builtin_constant_p(_weight)); \ - BUILD_BUG_ON_NOT_POWER_OF_2(_factor); \ - BUILD_BUG_ON_NOT_POWER_OF_2(_weight); \ + BUILD_BUG_ON(!__builtin_constant_p(_precision)); \ + BUILD_BUG_ON(!__builtin_constant_p(_weight_rcp)); \ + /* \ + * Even if you want to feed it just 0/1 you should have \ + * some bits for the non-fractional part... \ + */ \ + BUILD_BUG_ON((_precision) > 30); \ + BUILD_BUG_ON_NOT_POWER_OF_2(_weight_rcp); \ e->internal = 0; \ } \ static inline unsigned long \ ewma_##name##_read(struct ewma_##name *e) \ { \ - BUILD_BUG_ON(!__builtin_constant_p(_factor)); \ - BUILD_BUG_ON(!__builtin_constant_p(_weight)); \ - BUILD_BUG_ON_NOT_POWER_OF_2(_factor); \ - BUILD_BUG_ON_NOT_POWER_OF_2(_weight); \ - return e->internal >> ilog2(_factor); \ + BUILD_BUG_ON(!__builtin_constant_p(_precision)); \ + BUILD_BUG_ON(!__builtin_constant_p(_weight_rcp)); \ + BUILD_BUG_ON((_precision) > 30); \ + BUILD_BUG_ON_NOT_POWER_OF_2(_weight_rcp); \ + return e->internal >> (_precision); \ } \ static inline void ewma_##name##_add(struct ewma_##name *e, \ unsigned long val) \ { \ unsigned long internal = ACCESS_ONCE(e->internal); \ - unsigned long weight = ilog2(_weight); \ - unsigned long factor = ilog2(_factor); \ + unsigned long weight_rcp = ilog2(_weight_rcp); \ + unsigned long precision = _precision; \ \ - BUILD_BUG_ON(!__builtin_constant_p(_factor)); \ - BUILD_BUG_ON(!__builtin_constant_p(_weight)); \ - BUILD_BUG_ON_NOT_POWER_OF_2(_factor); \ - BUILD_BUG_ON_NOT_POWER_OF_2(_weight); \ + BUILD_BUG_ON(!__builtin_constant_p(_precision)); \ + BUILD_BUG_ON(!__builtin_constant_p(_weight_rcp)); \ + BUILD_BUG_ON((_precision) > 30); \ + BUILD_BUG_ON_NOT_POWER_OF_2(_weight_rcp); \ \ ACCESS_ONCE(e->internal) = internal ? \ - (((internal << weight) - internal) + \ - (val << factor)) >> weight : \ - (val << factor); \ + (((internal << weight_rcp) - internal) + \ + (val << precision)) >> weight_rcp : \ + (val << precision); \ } -#endif /* < KERNEL_VERSION(4, 3, 0) */ - #endif /* _NET_BATMAN_ADV_COMPAT_LINUX_AVERAGE_H */ diff --git a/net/batman-adv/types.h b/net/batman-adv/types.h index 8f64a5c0..66b25e41 100644 --- a/net/batman-adv/types.h +++ b/net/batman-adv/types.h @@ -402,7 +402,7 @@ struct batadv_gw_node { struct rcu_head rcu; }; -DECLARE_EWMA(throughput, 1024, 8) +DECLARE_EWMA(throughput, 10, 8) /** * struct batadv_hardif_neigh_node_bat_v - B.A.T.M.A.N. V private neighbor