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=-3.6 required=3.0 tests=BAYES_00,DKIM_INVALID, DKIM_SIGNED,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_HELO_NONE, SPF_PASS autolearn=no 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 E6582C48BE5 for ; Thu, 17 Jun 2021 06:07:46 +0000 (UTC) Received: from mm01.cs.columbia.edu (mm01.cs.columbia.edu [128.59.11.253]) by mail.kernel.org (Postfix) with ESMTP id 6C16D61019 for ; Thu, 17 Jun 2021 06:07:46 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 6C16D61019 Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=linuxfoundation.org Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=kvmarm-bounces@lists.cs.columbia.edu Received: from localhost (localhost [127.0.0.1]) by mm01.cs.columbia.edu (Postfix) with ESMTP id 0EDB540762; Thu, 17 Jun 2021 02:07:46 -0400 (EDT) X-Virus-Scanned: at lists.cs.columbia.edu Authentication-Results: mm01.cs.columbia.edu (amavisd-new); dkim=softfail (fail, message has been altered) header.i=@linuxfoundation.org Received: from mm01.cs.columbia.edu ([127.0.0.1]) by localhost (mm01.cs.columbia.edu [127.0.0.1]) (amavisd-new, port 10024) with ESMTP id 11emR7Oadn4p; Thu, 17 Jun 2021 02:07:43 -0400 (EDT) Received: from mm01.cs.columbia.edu (localhost [127.0.0.1]) by mm01.cs.columbia.edu (Postfix) with ESMTP id 8DBFD49F82; Thu, 17 Jun 2021 02:07:43 -0400 (EDT) Received: from localhost (localhost [127.0.0.1]) by mm01.cs.columbia.edu (Postfix) with ESMTP id 0B81540762 for ; Thu, 17 Jun 2021 02:07:42 -0400 (EDT) X-Virus-Scanned: at lists.cs.columbia.edu Received: from mm01.cs.columbia.edu ([127.0.0.1]) by localhost (mm01.cs.columbia.edu [127.0.0.1]) (amavisd-new, port 10024) with ESMTP id J0Hfae2weXvb for ; Thu, 17 Jun 2021 02:07:41 -0400 (EDT) Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by mm01.cs.columbia.edu (Postfix) with ESMTPS id 0D694404F8 for ; Thu, 17 Jun 2021 02:07:41 -0400 (EDT) Received: by mail.kernel.org (Postfix) with ESMTPSA id 20D7461019; Thu, 17 Jun 2021 06:07:39 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1623910060; bh=RxxDN0+WJx8ilpW/G89Y9l2RP0sjoG+dzwtt9FWmNdo=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=O3pebzgE5nwbFTTzr0PIb9z/ZEgnnxnHesRDDy6lJTF8nybwSBUknD/QQcma5fFIi +yiHLSvYrwuvj0CXh+GKtYIRSaIhs66caI3lToxlN/iVYsN5GUwnDi1UL9OPBEfA7G EB3R+wnhzxf6jPmX6Xi7RyFfIrhgcZdXimzFlbiU= Date: Thu, 17 Jun 2021 08:07:36 +0200 From: Greg KH To: Jing Zhang Subject: Re: [PATCH v10 3/5] KVM: stats: Add documentation for binary statistics interface Message-ID: References: <20210617044146.2667540-1-jingzhangos@google.com> <20210617044146.2667540-4-jingzhangos@google.com> MIME-Version: 1.0 Content-Disposition: inline In-Reply-To: <20210617044146.2667540-4-jingzhangos@google.com> Cc: KVM , David Hildenbrand , Paul Mackerras , Linuxkselftest , Claudio Imbrenda , Will Deacon , KVMARM , Emanuele Giuseppe Esposito , LinuxS390 , Janosch Frank , Marc Zyngier , Huacai Chen , Christian Borntraeger , Aleksandar Markovic , David Rientjes , KVMPPC , Krish Sadhukhan , David Matlack , Jim Mattson , Thomas Bogendoerfer , Sean Christopherson , Cornelia Huck , Peter Shier , LinuxMIPS , Paolo Bonzini , Vitaly Kuznetsov X-BeenThere: kvmarm@lists.cs.columbia.edu X-Mailman-Version: 2.1.14 Precedence: list List-Id: Where KVM/ARM decisions are made List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Errors-To: kvmarm-bounces@lists.cs.columbia.edu Sender: kvmarm-bounces@lists.cs.columbia.edu On Thu, Jun 17, 2021 at 04:41:44AM +0000, Jing Zhang wrote: > This new API provides a file descriptor for every VM and VCPU to read > KVM statistics data in binary format. > It is meant to provide a lightweight, flexible, scalable and efficient > lock-free solution for user space telemetry applications to pull the > statistics data periodically for large scale systems. The pulling > frequency could be as high as a few times per second. > The statistics descriptors are defined by KVM in kernel and can be > by userspace to discover VM/VCPU statistics during the one-time setup > stage. > The statistics data itself could be read out by userspace telemetry > periodically without any extra parsing or setup effort. Do you have a pointer to userspace code that can do such a thing that others can use? We do not like adding apis to the kernel without at least seeing the user of those apis, especially for complex things like this. Ideally you would include some library code in the kernel tree itself that everyone can use for this for their own programs. You have provided a test which is great, but how do we know it works for "real" usages? thanks, greg k-h _______________________________________________ kvmarm mailing list kvmarm@lists.cs.columbia.edu https://lists.cs.columbia.edu/mailman/listinfo/kvmarm