From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mail-pg1-f202.google.com (mail-pg1-f202.google.com [209.85.215.202]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 026763EA9A for ; Fri, 16 Aug 2024 04:33:03 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=209.85.215.202 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1723782785; cv=none; b=kxTFx8wDBA9YKasynexezs6u5V2SLB/pUA77xmb+M9HOjQqXW2bzJ9yhRWzkZpXgW5pWfiVEqytLExPR8mqC2PvvDSa9OUiSn8pbK0RxLNa7R11ir6s3Im9nrKKH5j9rUPiIAJDXsXPmqDh6Rsnx9MKkvNgDKInH87IdHqsgXqA= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1723782785; c=relaxed/simple; bh=gKYcw8BFgqyCG9U8fSFU4vcznAROy4MCcrvxbpOoMf8=; h=Date:In-Reply-To:Mime-Version:References:Message-ID:Subject:From: To:Cc:Content-Type; b=GTBh4XO8Z1D0Kr30r+bTMpghBenSYut6qsA02DkNVP4aXD5taKQd4dthS0n/nLM8u7JRmTw8LYaNJHVB2/P9JcIfbnYLdulaYsOhMeu8ze2UVW5Du0hiaYeaff7cPw7J/CuOkBpgk25CaHdYLBRU1G+fUS8iaArLygDUWSPdvbA= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=reject dis=none) header.from=google.com; spf=pass smtp.mailfrom=flex--seanjc.bounces.google.com; dkim=pass (2048-bit key) header.d=google.com header.i=@google.com header.b=iZQ52Jaq; arc=none smtp.client-ip=209.85.215.202 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=reject dis=none) header.from=google.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=flex--seanjc.bounces.google.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=google.com header.i=@google.com header.b="iZQ52Jaq" Received: by mail-pg1-f202.google.com with SMTP id 41be03b00d2f7-7ad78c1a019so1567679a12.2 for ; Thu, 15 Aug 2024 21:33:03 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20230601; t=1723782783; x=1724387583; darn=vger.kernel.org; h=cc:to:from:subject:message-id:references:mime-version:in-reply-to :date:from:to:cc:subject:date:message-id:reply-to; bh=oAY+2mnkmDOyE0/LDnygIPe0uyeLZUFD8yCrWWXulvA=; b=iZQ52JaqU0h2XDD9kTGwW2H96ai/m2b2BDE+zRVKxNkK63hkduLx4kS35y/EI4hu8C Xg+g96Ij2dOUhCSzb4Ws6fqtpDmvzNGUYKRS50s6lffYYifqS6PQ+GMoJPwB0TWcts6D PazoAlvFpEDbWbTH8ztc1E4MMvMAOAfyACW+x+B4hcrEJqqX/LGWaBXhQnPzWt+93jxg s/kPh2leL5+Sg6zzUUZJnIGJ+KlrC+UjZgzH6p5YpSoi+Oi2kYdibQKOXVujtAqN5Cze 70b2hGpbLP1jAAWfwAyVtePtTHeIP3Ph3c/jX9HqQg+2wLBPAek1j9jQ9Vt9YjwY+qoz sd7w== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20230601; t=1723782783; x=1724387583; h=cc:to:from:subject:message-id:references:mime-version:in-reply-to :date:x-gm-message-state:from:to:cc:subject:date:message-id:reply-to; bh=oAY+2mnkmDOyE0/LDnygIPe0uyeLZUFD8yCrWWXulvA=; b=xVjWrI5YMhDy6IK0JVXY/hxW3c6tdBOXIHjE26bRxIuvF2xS3YLlX8MaC3M6mQsn02 ZcUF2Ufy+JIchQVeLVlD1hGEgZXUVlpdDzX4LWgFoe6dgodg/GDvUjQ5v6dFBW1PVfEi 8eIqFTcNcx7TkTM0mRssdBMEPHGpJB49wziZlkC3OKR/wsLDKn3Ce5k1f5jFCACR3psh lXtL6cDCCmsiEsuWP6ZNWw87w06l+v8PiPKHqsPo7xBZ9DiDBlbQLkE3FZnACsqyL55E d9KCSud1wt5gTI/VvhmNbTGtl1HZuAvA9k26vbHdbkd3k+71qfWkRjQkSFBFhRMCAwRr fZxg== X-Forwarded-Encrypted: i=1; AJvYcCXjyXJENC2yEKHAcU5JYn6j53UX1dEBaW9omCzUppMaSw/hcDpGR+5X/4iBxdlkEkF7elonj0H/j6+zfs7K432rMA3KNNrbtA+o X-Gm-Message-State: AOJu0Yw695BwoTHxNBO1eQYnyc8uLsEZvzpfip5l8Lk/7Tl3rTMudTLu liowpdJTtdmlrxB7vTOxAhza+4L4Qa+6NvPhC/Z/gyOiedRkArBzBpC33fte3w6Hsz/lfOX9wXj D1w== X-Google-Smtp-Source: AGHT+IGfamVttf9aqtEoBOPzlIFrtjRPALYYklisneGw/z9Eb5n0QP2E9U6LZwfDLsshphmMuB6L9EZEGXA= X-Received: from zagreus.c.googlers.com ([fda3:e722:ac3:cc00:7f:e700:c0a8:5c37]) (user=seanjc job=sendgmr) by 2002:a17:902:ca05:b0:1fb:a38b:c59d with SMTP id d9443c01a7336-20203f391ffmr58715ad.7.1723782783028; Thu, 15 Aug 2024 21:33:03 -0700 (PDT) Date: Thu, 15 Aug 2024 21:33:01 -0700 In-Reply-To: <20240522001817.619072-20-dwmw2@infradead.org> Precedence: bulk X-Mailing-List: linux-doc@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: Mime-Version: 1.0 References: <20240522001817.619072-1-dwmw2@infradead.org> <20240522001817.619072-20-dwmw2@infradead.org> Message-ID: Subject: Re: [RFC PATCH v3 19/21] KVM: x86: Avoid periodic KVM clock updates in master clock mode From: Sean Christopherson To: David Woodhouse Cc: kvm@vger.kernel.org, Paolo Bonzini , Jonathan Corbet , Thomas Gleixner , Ingo Molnar , Borislav Petkov , Dave Hansen , x86@kernel.org, "H. Peter Anvin" , Paul Durrant , Peter Zijlstra , Juri Lelli , Vincent Guittot , Dietmar Eggemann , Steven Rostedt , Ben Segall , Mel Gorman , Daniel Bristot de Oliveira , Valentin Schneider , Shuah Khan , linux-doc@vger.kernel.org, linux-kernel@vger.kernel.org, jalliste@amazon.co.uk, sveith@amazon.de, zide.chen@intel.com, Dongli Zhang , Chenyi Qiang Content-Type: text/plain; charset="us-ascii" On Wed, May 22, 2024, David Woodhouse wrote: > From: David Woodhouse > > When the KVM clock is in master clock mode, updating the KVM clock is > pointless. Please explain why it's pointless. I almost feel bad asking you to elaborate since you've written wonderful changelogs for so many other patches, but far too many of the (historical) kvmclock commits assume the reader is some omniscient being, and it's definitely contributed to things getting into such a mess state. > Let the periodic work 'expire', and start it running again > from kvm_end_pvclock_update() if the master clock mode is ever turned > off again.