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=-5.1 required=3.0 tests=BAYES_00,DKIM_INVALID, DKIM_SIGNED,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,NICE_REPLY_A, SPF_HELO_NONE,SPF_PASS,USER_AGENT_SANE_1 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 D0655C433F5 for ; Wed, 22 Sep 2021 15:37:45 +0000 (UTC) Received: from mm01.cs.columbia.edu (mm01.cs.columbia.edu [128.59.11.253]) by mail.kernel.org (Postfix) with ESMTP id 2D749610A1 for ; Wed, 22 Sep 2021 15:37:45 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.4.1 mail.kernel.org 2D749610A1 Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=redhat.com Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=lists.cs.columbia.edu Received: from localhost (localhost [127.0.0.1]) by mm01.cs.columbia.edu (Postfix) with ESMTP id 95AEB4A500; Wed, 22 Sep 2021 11:37:44 -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=@redhat.com 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 G2jXkYyd8gum; Wed, 22 Sep 2021 11:37:43 -0400 (EDT) Received: from mm01.cs.columbia.edu (localhost [127.0.0.1]) by mm01.cs.columbia.edu (Postfix) with ESMTP id 863644B08B; Wed, 22 Sep 2021 11:37:43 -0400 (EDT) Received: from localhost (localhost [127.0.0.1]) by mm01.cs.columbia.edu (Postfix) with ESMTP id 544764A500 for ; Wed, 22 Sep 2021 11:37:42 -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 FaNqEWWiGQ88 for ; Wed, 22 Sep 2021 11:37:41 -0400 (EDT) Received: from us-smtp-delivery-124.mimecast.com (us-smtp-delivery-124.mimecast.com [216.205.24.124]) by mm01.cs.columbia.edu (Postfix) with ESMTP id 4F69D40256 for ; Wed, 22 Sep 2021 11:37:41 -0400 (EDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1632325061; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=yPMfBTlyhQaNIBRsQlgsKkEXI7vjlBDH2c8APmBdvAw=; b=GLJwTkgLpxnv7yuh8KpMLB5Vy7ZqEZowHFJ5LQOlC0yzN3/ptUE8CmqFDFRTXVR/CXglrk LcNg7D5OfzbvsLGv6+UpZR4q5FDz2IN36UgEo/3H/W5tIOwooBtgSjmbSQNjk7/aXgrl+7 hnL/4zTkTWSphH5f8WX1eR87Rt9XWhA= Received: from mail-ed1-f70.google.com (mail-ed1-f70.google.com [209.85.208.70]) (Using TLS) by relay.mimecast.com with ESMTP id us-mta-333-bqdcXD5mOsaloew4oLDTFA-1; Wed, 22 Sep 2021 11:37:38 -0400 X-MC-Unique: bqdcXD5mOsaloew4oLDTFA-1 Received: by mail-ed1-f70.google.com with SMTP id s12-20020a05640217cc00b003cde58450f1so3525562edy.9 for ; Wed, 22 Sep 2021 08:37:38 -0700 (PDT) X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; h=x-gm-message-state:subject:to:cc:references:from:message-id:date :user-agent:mime-version:in-reply-to:content-language :content-transfer-encoding; bh=yPMfBTlyhQaNIBRsQlgsKkEXI7vjlBDH2c8APmBdvAw=; b=KhheC1bsm5deZKDWenZMqO//Ao/N1Mud4gDNXV4ThrCtbdap5zPhVBy5r4WxPL6X88 A/2/n1utwnF+PYmapFXjDh1CmHixa/R3KwOkBI+OycudC2opNBgA3raLEh0SS/ZWD8vt r587jJ7EkxIiy1K940PlUQCqAJb2M0+rHiJ2aWvkCRIdQBbKAIA65m9a0gXKPw6yZaTz qWZ3fz26SknUDc4i5LOBM4BR1c/ZCT8fMSnA+y1vJrSu6Lw4280re6+jjpqx3ZFyE0K7 zeSTdmDM9iX26NmyVLy1FqWtRRlEIDdkE07mqBf8JfkdsExBwUFkKsum/tHrgxwQIDVB q+aA== X-Gm-Message-State: AOAM531DzUFuM5Jwi+G4HU2FQ8pkwNs61PM9j+gvUH14w0+ac2FS0aHT C67HcwriE8G0YG/7KlkyKErXaCNq3tTFHmDnqLR+ywSc+Fe7XPpGLzV1+eckzGxBzwJTe7MU1EV H8xgqeMttlHmjnZ8isXsDK+Sa X-Received: by 2002:a17:907:1df1:: with SMTP id og49mr176120ejc.35.1632325057663; Wed, 22 Sep 2021 08:37:37 -0700 (PDT) X-Google-Smtp-Source: ABdhPJxqc1iXc2OLrx6isUvPIHnN9Gan4Ne4+V8C0dmc4M3Gy8q4yKHumt8T875e2Dt+Me/ihh1nbg== X-Received: by 2002:a17:907:1df1:: with SMTP id og49mr176096ejc.35.1632325057433; Wed, 22 Sep 2021 08:37:37 -0700 (PDT) Received: from ?IPv6:2001:b07:6468:f312:c8dd:75d4:99ab:290a? ([2001:b07:6468:f312:c8dd:75d4:99ab:290a]) by smtp.gmail.com with ESMTPSA id z20sm1398413edl.61.2021.09.22.08.37.36 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Wed, 22 Sep 2021 08:37:36 -0700 (PDT) Subject: Re: [PATCH v1 3/3] KVM: arm64: Add histogram stats for handling time of arch specific exit reasons To: Marc Zyngier , Jing Zhang References: <20210922010851.2312845-1-jingzhangos@google.com> <20210922010851.2312845-3-jingzhangos@google.com> <87czp0voqg.wl-maz@kernel.org> From: Paolo Bonzini Message-ID: Date: Wed, 22 Sep 2021 17:37:35 +0200 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:78.0) Gecko/20100101 Thunderbird/78.11.0 MIME-Version: 1.0 In-Reply-To: <87czp0voqg.wl-maz@kernel.org> Authentication-Results: relay.mimecast.com; auth=pass smtp.auth=CUSA124A263 smtp.mailfrom=pbonzini@redhat.com X-Mimecast-Spam-Score: 0 X-Mimecast-Originator: redhat.com Content-Language: en-US Cc: KVM , Sean Christopherson , Peter Shier , David Matlack , Will Deacon , KVMARM 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-Transfer-Encoding: 7bit Content-Type: text/plain; charset="us-ascii"; Format="flowed" Errors-To: kvmarm-bounces@lists.cs.columbia.edu Sender: kvmarm-bounces@lists.cs.columbia.edu On 22/09/21 13:22, Marc Zyngier wrote: > Frankly, this is a job for BPF and the tracing subsystem, not for some > hardcoded syndrome accounting. It would allow to extract meaningful > information, prevent bloat, and crucially make it optional. Even empty > trace points like the ones used in the scheduler would be infinitely > better than this (load your own module that hooks into these trace > points, expose the data you want, any way you want). I agree. I had left out for later the similar series you had for x86, but I felt the same as Marc; even just counting the number of occurrences of each exit reason is a nontrivial amount of memory to spend on each vCPU. Paolo _______________________________________________ kvmarm mailing list kvmarm@lists.cs.columbia.edu https://lists.cs.columbia.edu/mailman/listinfo/kvmarm