From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-2.3 required=3.0 tests=DKIM_INVALID,DKIM_SIGNED, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_PASS,USER_AGENT_MUTT autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id CB4C0C0044C for ; Wed, 7 Nov 2018 13:16:41 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 8776B2086B for ; Wed, 7 Nov 2018 13:16:41 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=fail reason="signature verification failed" (2048-bit key) header.d=infradead.org header.i=@infradead.org header.b="dONH3Hki" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 8776B2086B Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=infradead.org Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=linux-kernel-owner@vger.kernel.org Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727710AbeKGWrA (ORCPT ); Wed, 7 Nov 2018 17:47:00 -0500 Received: from bombadil.infradead.org ([198.137.202.133]:38220 "EHLO bombadil.infradead.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727534AbeKGWrA (ORCPT ); Wed, 7 Nov 2018 17:47:00 -0500 DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=infradead.org; s=bombadil.20170209; h=In-Reply-To:Content-Type:MIME-Version :References:Message-ID:Subject:Cc:To:From:Date:Sender:Reply-To: Content-Transfer-Encoding:Content-ID:Content-Description:Resent-Date: Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID:List-Id: List-Help:List-Unsubscribe:List-Subscribe:List-Post:List-Owner:List-Archive; bh=ghEFjup3LUn+tpj9gyuDotc1TfXh7DnCI2mdqd29zjs=; b=dONH3HkiCHxh5xA3aCBUS4tsv fkoLnudiP3rXlT9ziC/Ajdhgmf83Ozx5Q7twB3OV9LJYOsh0gIURbVbNbfjMRvB9m3t2kVSqIN2g+ V0R1pnw33NplLbRUevdkrdG2+hsDDUPMOIdXJGer+iOtUHcBPd8KW4Q3jX/1bRZLM3B+gjbaUTLoG MLLrwy6TvmTd+ybeeL76VyUfdve8NKIabdyjtMj9eutc603P2Id6+ePemcQjz+xz4SxSxv0bAFadk 9gDre/hM7vMfTiUyMsulkyyHMCxCqEiUxDjgamWnnV0OtMYAgmLVSha3PhoEdd/3w2KnvvVj6D3lA QM9+VYEHA==; Received: from j217100.upc-j.chello.nl ([24.132.217.100] helo=hirez.programming.kicks-ass.net) by bombadil.infradead.org with esmtpsa (Exim 4.90_1 #2 (Red Hat Linux)) id 1gKNhD-0001Pf-2N; Wed, 07 Nov 2018 13:16:35 +0000 Received: by hirez.programming.kicks-ass.net (Postfix, from userid 1000) id 5B73A20298C0C; Wed, 7 Nov 2018 14:16:32 +0100 (CET) Date: Wed, 7 Nov 2018 14:16:32 +0100 From: Peter Zijlstra To: Patrick Bellasi Cc: linux-kernel@vger.kernel.org, linux-pm@vger.kernel.org, Ingo Molnar , Tejun Heo , "Rafael J . Wysocki" , Vincent Guittot , Viresh Kumar , Paul Turner , Quentin Perret , Dietmar Eggemann , Morten Rasmussen , Juri Lelli , Todd Kjos , Joel Fernandes , Steve Muckle , Suren Baghdasaryan Subject: Re: [PATCH v5 03/15] sched/core: uclamp: map TASK's clamp values into CPU's clamp groups Message-ID: <20181107131632.GP9781@hirez.programming.kicks-ass.net> References: <20181029183311.29175-1-patrick.bellasi@arm.com> <20181029183311.29175-4-patrick.bellasi@arm.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20181029183311.29175-4-patrick.bellasi@arm.com> User-Agent: Mutt/1.10.1 (2018-07-13) Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Mon, Oct 29, 2018 at 06:32:57PM +0000, Patrick Bellasi wrote: > +static void uclamp_group_put(unsigned int clamp_id, unsigned int group_id) > { > + union uclamp_map *uc_maps = &uclamp_maps[clamp_id][0]; > + union uclamp_map uc_map_old, uc_map_new; > + long res; > + > +retry: > + > + uc_map_old.data = atomic_long_read(&uc_maps[group_id].adata); > + uc_map_new = uc_map_old; > + uc_map_new.se_count -= 1; > + res = atomic_long_cmpxchg(&uc_maps[group_id].adata, > + uc_map_old.data, uc_map_new.data); > + if (res != uc_map_old.data) > + goto retry; > +} Please write cmpxchg loops in the form: atomic_long_t *ptr = &uclamp_maps[clamp_id][group_id].adata; union uclamp_map old, new; old.data = atomic_long_read(ptr); do { new.data = old.data; new.se_cound--; } while (!atomic_long_try_cmpxchg(ptr, &old.data, new.data)); (same for all the others of course)