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 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 6357BC433EF for ; Fri, 8 Oct 2021 14:09:35 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 47AF361042 for ; Fri, 8 Oct 2021 14:09:35 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S232821AbhJHOL3 (ORCPT ); Fri, 8 Oct 2021 10:11:29 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:42444 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S237830AbhJHOL3 (ORCPT ); Fri, 8 Oct 2021 10:11:29 -0400 Received: from mail-il1-x131.google.com (mail-il1-x131.google.com [IPv6:2607:f8b0:4864:20::131]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 0650DC061755 for ; Fri, 8 Oct 2021 07:09:34 -0700 (PDT) Received: by mail-il1-x131.google.com with SMTP id d11so10128560ilc.8 for ; Fri, 08 Oct 2021 07:09:34 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20210112; h=mime-version:from:date:message-id:subject:to; bh=OAyahn7hTcOi0w3EhYRbF/EsHfrIHNXVi748AsP0i3I=; b=h7zLI6WEEbVQxFe1z67p3QtoaCqLwhz/c99O3EInT8dLR/8kumNQfj+kJrWw8ZfWtH yF0uHhvP2tXfDTUFK2+R25GrkugKuqwhfcOClCcqjJHseUIGzU4yuWGpnG2+ndfEH9XL LvoddvOTmK4m5X444cGaNwCVGJlbeo2688tBDtRmAR5hapSc/DSSOOZmCaGdmWMwk203 ZvErcy88QtIq47Nh1BhHwyhuNoGdSQBX313duoew4Zb0ji9NG2ss0BNmYH7uNI8KlL/3 4r05YTV07esPZdmzRxLfjObEx1OEg4d5H6ATGgOQpqEDi0mvMCAqRM2jMhld9a2YXQn2 cKsA== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; h=x-gm-message-state:mime-version:from:date:message-id:subject:to; bh=OAyahn7hTcOi0w3EhYRbF/EsHfrIHNXVi748AsP0i3I=; b=e8ZTuQDR8hyb7fkNoZUU5WFIVUOrf90JaJfNS0p94oWfut+AyKgYy6e3xecE5gUwy5 4bs+SsdIH8Kdp7oNuCP803vsLxyGffEKUyKAT7Ont5/7VxkKNTZbevKHFqkj/NUjYPrE tewrErEfZlsauQ6AF4CmQgAvxExBAMdqStl7r7pqXlp/gd7b8QwWthFXBiFmPCILSnDz Nmx0YSqil3s0fKfkFoTvmo36piQZkHRBsIwx+QNE8fbP45d+gJa1pMdT/unJjR6PD1P0 NP6Zucxz4OA3Fodqmg8pF3wYkHBYP4l/VIfqfua8Ey+mmLisXeOp9Xt35MEq+Im7wYdm zhRw== X-Gm-Message-State: AOAM53149WKRRKd9oIcgYeurT5+IPdrsKuG9oBxmk2yrN1B78goNiXkN MpFWGj3hb39yaEGE7mQ94A2PFyP0x63KcE3CNg1z4cpilGs= X-Google-Smtp-Source: ABdhPJydRG71ui1pa2OgmiiriomgA/+3l96QZgmeJQpB4sBmBWrvu/a8KnUc0+JssnqiV9TXUn2HrxfQPTpkrvGM5f8= X-Received: by 2002:a05:6e02:184f:: with SMTP id b15mr8267781ilv.187.1633702173215; Fri, 08 Oct 2021 07:09:33 -0700 (PDT) MIME-Version: 1.0 From: "Y.G Kumar" Date: Fri, 8 Oct 2021 19:39:22 +0530 Message-ID: Subject: Need Information To: kvm@vger.kernel.org Content-Type: text/plain; charset="UTF-8" Precedence: bulk List-ID: X-Mailing-List: kvm@vger.kernel.org Hi, I am trying to understand the concept of cpu steal time. I have a few questions about it. According to the link https://scoutapm.com/blog/understanding-cpu-steal-time-when-should-you-be-worried , it is defined as follows: "Steal time is the percentage of time a virtual CPU waits for a real CPU while the hypervisor is servicing another virtual processor." I have two questions regarding that. 1. What do we mean by "percentage of time" ? Which time is it alluding to ? Is it the "cpu time" allocated by the scheduler to that kvm process ? Or, is it the general waiting time that vcpu process has to wait in the run queue before getting the cpu for execution ? If this is true, then it is normal for that vcpu process like any other process on the system to wait in the runqueue. Then what is this fuss about ? 2. How can we read this steal time ? Can we see it from within the vm and from the hypervisor host also ? If so, how ? Does this mean that we cant see the "st" field if we execute the top command on a server without any hypervisor ? Please explain. Thanks Kumar