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 kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by smtp.lore.kernel.org (Postfix) with ESMTP id B5BD6C64EC4 for ; Wed, 1 Mar 2023 03:10:10 +0000 (UTC) Received: by kanga.kvack.org (Postfix) id 44FCF6B0071; Tue, 28 Feb 2023 22:10:10 -0500 (EST) Received: by kanga.kvack.org (Postfix, from userid 40) id 3FE896B0072; Tue, 28 Feb 2023 22:10:10 -0500 (EST) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 2ED996B0073; Tue, 28 Feb 2023 22:10:10 -0500 (EST) X-Delivered-To: linux-mm@kvack.org Received: from relay.hostedemail.com (smtprelay0013.hostedemail.com [216.40.44.13]) by kanga.kvack.org (Postfix) with ESMTP id 2064D6B0071 for ; Tue, 28 Feb 2023 22:10:10 -0500 (EST) Received: from smtpin21.hostedemail.com (a10.router.float.18 [10.200.18.1]) by unirelay04.hostedemail.com (Postfix) with ESMTP id C173A1A0EC2 for ; Wed, 1 Mar 2023 03:10:09 +0000 (UTC) X-FDA: 80518850538.21.6279CBF Received: from mail-il1-f169.google.com (mail-il1-f169.google.com [209.85.166.169]) by imf22.hostedemail.com (Postfix) with ESMTP id 0B63CC000E for ; Wed, 1 Mar 2023 03:10:07 +0000 (UTC) Authentication-Results: imf22.hostedemail.com; dkim=pass header.d=google.com header.s=20210112 header.b=HLGtfGLq; spf=pass (imf22.hostedemail.com: domain of talumbau@google.com designates 209.85.166.169 as permitted sender) smtp.mailfrom=talumbau@google.com; dmarc=pass (policy=reject) header.from=google.com ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=hostedemail.com; s=arc-20220608; t=1677640208; h=from:from:sender: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: in-reply-to:in-reply-to:references:references:dkim-signature; bh=bqG1KiFqgV3w84xKqssw1SPB+U/GqHN3EEE5xSj5hng=; b=4tQXCbITSbrYxXssrOUjAMhPgGNivyG9YD9qeZf4VRjB/3RNm5iX7X7AxgpR0KuTUAcUeO nGRzrdaoWpcrPP/P2/JGiyt/blsqPaEbLOmfs2H/9sonJsimQu2RchHGTuI+Ae1+q2XPnb B4vlMmVmjYC7oZRfSuUNmgK7/VnY2Ak= ARC-Authentication-Results: i=1; imf22.hostedemail.com; dkim=pass header.d=google.com header.s=20210112 header.b=HLGtfGLq; spf=pass (imf22.hostedemail.com: domain of talumbau@google.com designates 209.85.166.169 as permitted sender) smtp.mailfrom=talumbau@google.com; dmarc=pass (policy=reject) header.from=google.com ARC-Seal: i=1; s=arc-20220608; d=hostedemail.com; t=1677640208; a=rsa-sha256; cv=none; b=kBImT1XFVwrH3ZvntP0LXDUxi7tCWg5q3sub3axGPkMkk/zgc0apDiQ0Q2TadD3U9XOLFD 3on77bpHRNFK5bx1e3IxmAzEUX1q6UmlzxPzDgmieZXhyLw75902B1IQy4F5kfSCLrXE7r nYEDu0j1zh0z2Yra+CnrYQ1orc/AsdI= Received: by mail-il1-f169.google.com with SMTP id l2so7607781ilg.7 for ; Tue, 28 Feb 2023 19:10:07 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20210112; t=1677640207; h=cc:to:subject:message-id:date:from:in-reply-to:references :mime-version:from:to:cc:subject:date:message-id:reply-to; bh=bqG1KiFqgV3w84xKqssw1SPB+U/GqHN3EEE5xSj5hng=; b=HLGtfGLqyZrz9qE+vrLLF/Izwf97zYP7hrqe7SpoIUf92WQ6UbuN9d4v9ENrJgcing Juy0vYNns9lcVExdato6plQSq7QIMf9bT/3ccDwAYCP0D7pUWnPawBKnWaacgbyzYo+R 7hbepc6mKA5FrVtJfmtjzabo7nlOzjcQzeHp6I+r+Sk/C6IWTqSPdMFZntXk6rbss3kc yyKgJ4O93OTIvErG6F7llYv3HoqMxKvHkYx6yd0DSAZ8BS+qaKqK4HMYc9Bnuu4lG++X GAqixIj8N2JduhPk4op3CkdVSlXy5zK4kNw/PPpOSUxNOhy10PYY9w4619C03S+aEOCk RZlg== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; t=1677640207; h=cc:to:subject:message-id:date:from:in-reply-to:references :mime-version:x-gm-message-state:from:to:cc:subject:date:message-id :reply-to; bh=bqG1KiFqgV3w84xKqssw1SPB+U/GqHN3EEE5xSj5hng=; b=N+PmuW1B/CfZTky4T9dU3vn0o7aOrI1j8UCjkPXRb0haLkbPojgS8zsDhrtsiz7bef Tvko9h3r/BkXVsaB60SgW6BkmjM7MQjqAN6QMRI9YGA53p1MPNd45ywMNiqFUKgOY7G/ GoQwpCxjYEc4Pff8pyxQCE9dq7k5gA4kvqAC7bgWRIBg4I5rzeHUG94Lee/cx3cBGf9A 54VYxclyh8CFOxktgsy5ORvPqJPgfKPHH+GyXgZID6/BCIVu5YfpVsbeKX/JF6Fj5aEM X3DQEcjUm2cRxg/bVuhET4kahwrdyMlJgenkRbSdN8ESee8K7HlGdu8D9VqJXhGQn2gj gBbw== X-Gm-Message-State: AO0yUKVL1Ms289ryCUDKZuuTVLvErGmvGFxtoxKO9qM2sOLTJZOgmljp FwpQUgxb50oMBOFAqeS2DlDCgToWmvkI8FtnD3eUyQ== X-Google-Smtp-Source: AK7set/yekZXkg/X6q8NMP9CV1gTkp5Y3/JMyipSTUG1B4yqnPiZ/XzWc4BnCYV6EgDuk/m3bfkoFnWjBu0lwfswpq8= X-Received: by 2002:a92:cdac:0:b0:317:6eac:97e1 with SMTP id g12-20020a92cdac000000b003176eac97e1mr3442073ild.0.1677640206998; Tue, 28 Feb 2023 19:10:06 -0800 (PST) MIME-Version: 1.0 References: <03c941dd-39a9-6775-ce4d-ff6ac9abffd7@amd.com> In-Reply-To: <03c941dd-39a9-6775-ce4d-ff6ac9abffd7@amd.com> From: "T.J. Alumbaugh" Date: Tue, 28 Feb 2023 20:09:30 -0700 Message-ID: Subject: Re: [LSF/MM/BPF TOPIC] VM Memory Overcommit To: "Gupta, Pankaj" Cc: lsf-pc@lists.linux-foundation.org, "Sudarshan Rajagopalan (QUIC)" , hch@lst.de, kai.huang@intel.com, David Hildenbrand , jon@nutanix.com, Yuanchu Xie , linux-mm Content-Type: text/plain; charset="UTF-8" X-Rspam-User: X-Rspamd-Server: rspam04 X-Rspamd-Queue-Id: 0B63CC000E X-Stat-Signature: q1mrmrn1kg1ubyebfcn41m3t13cum9k3 X-HE-Tag: 1677640207-177292 X-HE-Meta: U2FsdGVkX18tMBH0o72zb5gJHQtSHtCjgwpIEKn4EJtxDDhTN+TLbimdHwrhytVrvK4EhrTRhVUr/c8nD6VOQvjHnzeMQafTDGVZsv9lOltHnTFllJUecY86IlzAutPEQZ0uDLySaU3qGcOAprqbhMLU8NR0wAnXp+go8AnjEMmaunS6T1Ob4FYxJlRi/T0Ivy13I8BLhSL8kOrW4KiOpfPCr2+VEnbqz5kIns+7ij7qNNqArE8Yg/yHq2aY/B3XtP1+Bg8Gov5lbHZXuuCDAGdJVmWPnR/KamvTWf444gbFt4INF2KKFnujCPWHiMNjwFrnymcj8LIJOzvl6IcqINWG95jJbqXT6WAqp1aLDPwWLs6waRR/DchbmRV/bhgw/jVs5QR0Fu26Wz0flqXz0TzQo/eDnuUxGHaHI2O5J3cCIYcW8lk2zaoefvMHWSJvgYSQBTyjEqu2KsI75ciKKvCE4BijwOfUKIqp6Jpk/rm4p7lY8TzQv2JPgiIG4pLOjsel6t5WVT20/JkP0T0J0oldZWPdko6HcoD4S9m5UmXvdmFHrDiUnIAUz7JoWHW09Nj1WW7jR/LDfgvSw4yFOfnHT9ZZPFyNr4436FeesD80oQ26xJGe2IZmL7lSC2haCoSykEjA3pOLxg96DNPoJ+KO3UWUIPskDY/uE8Wx/a0CfTzozCGOoZjau7uZKJzCsX3cPci6ELJz/TMXkYX03c7FKWJZSoQz17fDzNwW/KcizisQLBw/ElfPR+Po7XRZf6DiOYZG7EnG27zhwhLidSWrs6VuALaKX1jQPobZharm/6gxww8kRYnkBdqpvxdBktD1P1w5LpyH8rlPNUU07zpaCGwPoDL7mws8Zfgn2zniyMiMtU/r+Fnjrgp8K7QaMLZ52AHtJq4blcqPB8ipK6HuHNJgV72qc/vbaUnYcfNR8ry2TizAwnDFnTxc54s2JBXpx/eUgRjiDag/Grz nYvg/hXS /f1Z9WOwfM1CI9FU0/KhcBNOpZZ8unnoRto/RRxt1+XK2S5CSGHC1FtcX6Ms+WC9hHen8r9raKt5yZAczJQBAjH0PLmou+1/mtO1QqgH7PYBakrW8NKY/V327dtfwnx7hHK8sRnYuWL/04VDylRqqHk46BQqps/huUavQXIy6fcVfroAbV+qWrVc+JVVEsl4kjM11cS4XToK9PjHSXJ0oPqcuQ0TcBWp4+bmeJIUK6iM5TdvzDoyYvYZEQ1mLNpnDhDIHgCWQbjvzR/4= X-Bogosity: Ham, tests=bogofilter, spamicity=0.000846, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: Hi Pankaj, On Mon, Feb 27, 2023 at 11:02 PM Gupta, Pankaj wrote: > > > - What kind/frequency of data we expect WSS would relay to the host in > good and worst case? > This is a good question. Right now, we communicate a histogram of page counts (not very much data) during periods of memory pressure, with user configurable rate limiting. The goal is to notify when it's important to take action, but we also allow the host to request a report. > - Thoughts already considered about the overhead VM will have based on > WSS relay data to the host and host taking action on the data? > > -- One thing iirc from the free page hinting design experiments is > preventing guest and host acting simultaneously (e.g for free) on > same page (pfn) and also reducing the overhead of sending data from > guest to host by sending the highest possible page order. > I think you are correct that the best way to reduce overhead is by sending the highest possible page order. So far we have not directly addressed this problem. The goal here is to solve the "when" and "how much" problems for balloon adjustment, which will go far in minimizing fragmentation caused by frequent balloon adjustments. But it seems clear that sending a higher page order is important too. > Maybe some of these or other similar techniques are already considered. > David's idea of pairing this capability with free page reporting (in the next reply on this thread) seems like an intriguing next step. -T.J.