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=-0.8 required=3.0 tests=DKIM_INVALID,DKIM_SIGNED, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_PASS,URIBL_BLOCKED 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 584B1C43381 for ; Wed, 27 Feb 2019 14:23:16 +0000 (UTC) Received: from bombadil.infradead.org (bombadil.infradead.org [198.137.202.133]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPS id 229842133D for ; Wed, 27 Feb 2019 14:23:16 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=fail reason="signature verification failed" (2048-bit key) header.d=lists.infradead.org header.i=@lists.infradead.org header.b="JaepHl27" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 229842133D Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=arm.com Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=linux-arm-kernel-bounces+infradead-linux-arm-kernel=archiver.kernel.org@lists.infradead.org DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=bombadil.20170209; h=Sender: Content-Transfer-Encoding:Content-Type:Cc:List-Subscribe:List-Help:List-Post: List-Archive:List-Unsubscribe:List-Id:In-Reply-To:MIME-Version:Date: Message-ID:From:References:To:Subject:Reply-To:Content-ID:Content-Description :Resent-Date:Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID: List-Owner; bh=qMs1RhHcNPiEu+FZK3HIKTmmcaMbD0It9Z8zLSsE8Jg=; b=JaepHl27yD7Lsl GsLTJn9qyfU5wcSkji5nW8BenveV8UugIAUuu5NRdxBSRM7b1UUOCRnC0ojYGrNIUCYI17QqA69wf zjws6XlpSTvbeoMkOgjz1iMhvzUgVSucUA7OHPjwCY0MbVtSCyGcP1KXSlosEtncaWilcc3lIvHFj vsBDw40OlfCI2wfGVvpIqaj5L7oP4kIXnK81AImVz5VBkPBQK8dcI+g1M4BSgr+0SCDNSUlBH/iJV KqgkuZ39812RxLy9ESx3YxbblJx15a7XwRtjStxe8ZyIKHNKUcLge9cTXW6Wsq0n1N2b74GrRc+Yo /86UH8uh9xePc28bkj4w==; Received: from localhost ([127.0.0.1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.90_1 #2 (Red Hat Linux)) id 1gz074-0003Qf-2g; Wed, 27 Feb 2019 14:23:10 +0000 Received: from usa-sjc-mx-foss1.foss.arm.com ([217.140.101.70] helo=foss.arm.com) by bombadil.infradead.org with esmtp (Exim 4.90_1 #2 (Red Hat Linux)) id 1gz070-0003QG-SG for linux-arm-kernel@lists.infradead.org; Wed, 27 Feb 2019 14:23:08 +0000 Received: from usa-sjc-imap-foss1.foss.arm.com (unknown [10.72.51.249]) by usa-sjc-mx-foss1.foss.arm.com (Postfix) with ESMTP id 5290A374; Wed, 27 Feb 2019 06:23:06 -0800 (PST) Received: from [10.1.196.72] (e119884-lin.cambridge.arm.com [10.1.196.72]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id D25FC3F5C1; Wed, 27 Feb 2019 06:23:03 -0800 (PST) Subject: Re: [PATCH v5 01/23] kernel: Standardize vdso_datapage To: Thomas Gleixner References: <20190222122430.21180-1-vincenzo.frascino@arm.com> <20190222122430.21180-2-vincenzo.frascino@arm.com> From: Vincenzo Frascino Message-ID: <3f7238b5-3357-3635-38f4-9eaa14e400c9@arm.com> Date: Wed, 27 Feb 2019 14:23:02 +0000 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:60.0) Gecko/20100101 Thunderbird/60.4.0 MIME-Version: 1.0 In-Reply-To: Content-Language: en-US X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20190227_062306_919529_E59ACCE5 X-CRM114-Status: GOOD ( 20.61 ) X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.21 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: linux-arch@vger.kernel.org, Shuah Khan , Arnd Bergmann , Catalin Marinas , Daniel Lezcano , Will Deacon , Russell King , Ralf Baechle , Mark Salyzyn , Paul Burton , Dmitry Safonov <0x7f454c46@gmail.com>, Rasmus Villemoes , Peter Collingbourne , linux-arm-kernel@lists.infradead.org Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+infradead-linux-arm-kernel=archiver.kernel.org@lists.infradead.org On 23/02/2019 16:51, Thomas Gleixner wrote: > On Fri, 22 Feb 2019, Vincenzo Frascino wrote: >> +/* >> + * There is one vdso_clocksource object in vvar for each vDSO clocksource >> + * (mono, raw). This struct is designed to keep vdso_data "cache-line friendly" >> + * and optimal in terms of access pattern. >> + * >> + * Note that mask and shift are the same for mono and raw. >> + */ >> +struct vdso_clocksource { >> + u64 mask; /* Clocksource mask */ >> + u32 mult; /* Clocksource multiplier */ >> + u32 shift; /* Clocksource shift */ > > Can you please get rid of the tail comments and use proper kerneldoc > format? > I will fix it in v6, thanks. >> +/* >> + * vdso_data will be accessed by 32 and 64 bit code at the same time >> + * so we should be careful before modifying this structure. >> + */ >> +struct vdso_data { >> + u32 seq; /* Timebase sequence counter */ >> + >> + s32 clock_mode; >> + u64 cycle_last; /* Timebase at clocksource init */ >> + >> + struct vdso_clocksource cs[CLOCKSOURCE_BASES]; > > Why would you need different clocksource parameters? That really bloats the > data structure and makes the cache access pattern worse. Also the vdso > update needs to copy the same data over and over for no value. > > The only clock ID which needs a different mult/shift would be > MONOTONIC_RAW, but if we expose that through the VDSO then we really can be > smarter than this. See incomplete and uncompilable patch below for > reference. You get the idea. > Ok, thank you for providing the reference code. I will update my patches in v6 accordingly. ... -- Regards, Vincenzo _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel