From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mails.dpdk.org (mails.dpdk.org [217.70.189.124]) by inbox.dpdk.org (Postfix) with ESMTP id 4444E45580; Thu, 4 Jul 2024 20:59:36 +0200 (CEST) Received: from mails.dpdk.org (localhost [127.0.0.1]) by mails.dpdk.org (Postfix) with ESMTP id 16E4A410F1; Thu, 4 Jul 2024 20:59:36 +0200 (CEST) Received: from fout2-smtp.messagingengine.com (fout2-smtp.messagingengine.com [103.168.172.145]) by mails.dpdk.org (Postfix) with ESMTP id 318C6402A7 for ; Thu, 4 Jul 2024 20:59:35 +0200 (CEST) Received: from compute2.internal (compute2.nyi.internal [10.202.2.46]) by mailfout.nyi.internal (Postfix) with ESMTP id 7127B1380155; Thu, 4 Jul 2024 14:59:34 -0400 (EDT) Received: from mailfrontend1 ([10.202.2.162]) by compute2.internal (MEProxy); Thu, 04 Jul 2024 14:59:34 -0400 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=monjalon.net; h= cc:cc:content-transfer-encoding:content-type:content-type:date :date:from:from:in-reply-to:in-reply-to:message-id:mime-version :references:reply-to:subject:subject:to:to; s=fm2; t=1720119574; x=1720205974; bh=btbUl0fMTXB/yD5swaft0RS9IYrXcm9gt+tZXvwxJKc=; b= SeS31hbPRAUL6E7w4T8X65x1fDtJbZGVqNRwzzM5kPLsNEvXho6E92gyJCNRw58R le/GOGf1BLPXEDz+/ZB1DzXh3buHK13F23giRO0szhJ/6RAgpgSx4191eb0Hi7y+ BsrVVvAyMsz/W8+B/5zXb5EQ5WyxgSIq3+sVeXdD3IokbTsm75uUQWjlqUNsOP1a Ace0lyUEgp9XF7Fk8hOBdeW1Wp5tV6ZeNoE2R9oRraFjWgH2deFxoC7t8cIJAZ8V yO/ZxXioWQ0DujXjqGlJWz6x2/sIxdabjZIWU68ydqDFWocOngbase5DNnMO3FC3 ygityL5War9O3TdGvWJeiw== DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d= messagingengine.com; h=cc:cc:content-transfer-encoding :content-type:content-type:date:date:feedback-id:feedback-id :from:from:in-reply-to:in-reply-to:message-id:mime-version :references:reply-to:subject:subject:to:to:x-me-proxy:x-me-proxy :x-me-sender:x-me-sender:x-sasl-enc; s=fm2; t=1720119574; x= 1720205974; bh=btbUl0fMTXB/yD5swaft0RS9IYrXcm9gt+tZXvwxJKc=; b=t zHT4JB6niSY7maJA2S9Bfd0APqzNdpNjWTMhLfAmwA23JsHlBRm9vU1cTZ0wbius uU+ugaLXbB29boPsQyXmObdmhn1qdd6mJ8INqI7Tw3g2c8bHsYRfdGQX6ilaujMo IsGqiXtLeye5VfGlEym2iK80ojxWGw9iHzbEZvttkSdFh2o8iEkfg6VWVWceMdZf 5S5wHfUDyVRFOHD/F2wdlpiUODuKq6ZGxl/jbXN91EglMUI7g7DBJ5uICRs0+zAQ YppLl4Csba/xKQKY94JYvHkp9R1twgSlwSjF6wNyipCFgzp/Q3iZCy/SDzcHJEeq LhE8tUBUJLbAA97Cqlt2g== X-ME-Sender: X-ME-Received: X-ME-Proxy-Cause: gggruggvucftvghtrhhoucdtuddrgeeftddrudelgdduvdelucetufdoteggodetrfdotf fvucfrrhhofhhilhgvmecuhfgrshhtofgrihhlpdfqfgfvpdfurfetoffkrfgpnffqhgen uceurghilhhouhhtmecufedttdenucesvcftvggtihhpihgvnhhtshculddquddttddmne cujfgurhephffvvefufffkjghfggfgtgesthhqredttddtjeenucfhrhhomhepvfhhohhm rghsucfoohhnjhgrlhhonhcuoehthhhomhgrshesmhhonhhjrghlohhnrdhnvghtqeenuc ggtffrrghtthgvrhhnpeegtddtleejjeegffekkeektdejvedtheevtdekiedvueeuvdei uddvleevjeeujeenucevlhhushhtvghrufhiiigvpedtnecurfgrrhgrmhepmhgrihhlfh hrohhmpehthhhomhgrshesmhhonhhjrghlohhnrdhnvght X-ME-Proxy: Feedback-ID: i47234305:Fastmail Received: by mail.messagingengine.com (Postfix) with ESMTPA; Thu, 4 Jul 2024 14:59:31 -0400 (EDT) From: Thomas Monjalon To: Stephen Hemminger Cc: Pavan Nikhilesh Bhagavatula , Wathsala Wathawana Vithanage , Tyler Retzlaff , Ruifeng Wang , "dev@dpdk.org" , nd , Dhruv Tripathi , Honnappa Nagarahalli , Jack Bond-Preston , Nick Connolly , Vinod Krishna , "david.marchand@redhat.com" Subject: Re: [PATCH v2 2/2] eal: add Arm WFET in power management intrinsics Date: Thu, 04 Jul 2024 20:59:29 +0200 Message-ID: <3741901.S9oNm88NmQ@thomas> In-Reply-To: <20240704075515.75a9a0cd@hermes.local> References: <20240604044401.3577707-2-wathsala.vithanage@arm.com> <4208140.dumfJixkPq@thomas> <20240704075515.75a9a0cd@hermes.local> MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable Content-Type: text/plain; charset="utf-8" X-BeenThere: dev@dpdk.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: DPDK patches and discussions List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: dev-bounces@dpdk.org 04/07/2024 16:55, Stephen Hemminger: > On Thu, 04 Jul 2024 16:14:42 +0200 > Thomas Monjalon wrote: >=20 > > > > Let=E2=80=99s ask Pavan why this flag is used in cn10k driver. > > > >=20 > > > > From our perspective, WFE is available on all the supported arm pla= tforms in > > > > DPDK. > > > > Therefore, RTE_ARM_USE_WFE should be treated as a flag to choose be= tween > > > > WFE > > > > and non-WFE code paths due to performance reasons rather than as a = flag > > > > that indicates > > > > the availability of the instruction on the target CPU. > > > > =20 > > >=20 > > > We are using this flag to allow application to choose between WFE and= non-WFE code path. > > > The non-WFE path performs slightly better. =20 > >=20 > > What's the benefit of the WFE path then? >=20 > WFE saves power at the expense of latency. Yes maybe there is a misunderstanding. Pavan can you confirm you were saying "throughput is better on non-WFE"? but "power consumption is lower on WFE path"? > Maybe some form of hybrid approach would work best and could > be always used. >=20 > For example, many implementations of mutex do a short spin poll > then fall back to a waiting primitive (like futex).