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=-1.0 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SPF_PASS autolearn=unavailable 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 CAFF0C10F09 for ; Fri, 8 Mar 2019 19:10:43 +0000 (UTC) Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by mail.kernel.org (Postfix) with ESMTP id 7B4EB206DF for ; Fri, 8 Mar 2019 19:10:43 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 7B4EB206DF Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=redhat.com Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=owner-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix) id 139E88E0003; Fri, 8 Mar 2019 14:10:43 -0500 (EST) Received: by kanga.kvack.org (Postfix, from userid 40) id 113188E0002; Fri, 8 Mar 2019 14:10:43 -0500 (EST) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 001568E0003; Fri, 8 Mar 2019 14:10:42 -0500 (EST) X-Delivered-To: linux-mm@kvack.org Received: from mail-qt1-f199.google.com (mail-qt1-f199.google.com [209.85.160.199]) by kanga.kvack.org (Postfix) with ESMTP id CD9948E0002 for ; Fri, 8 Mar 2019 14:10:42 -0500 (EST) Received: by mail-qt1-f199.google.com with SMTP id i3so19437129qtc.7 for ; Fri, 08 Mar 2019 11:10:42 -0800 (PST) X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-original-authentication-results:x-gm-message-state:subject:to:cc :references:from:openpgp:autocrypt:organization:message-id:date :user-agent:mime-version:in-reply-to; bh=FMBr24ynMW9XPu7VBssYQrMAzHMlm70SAIn8+HmMO90=; b=p3VELv89tgTMqepm3PKK3m8ulFRSAqwP6jtkNyI6p54fcmShzv0shgC6f6G/k78hUc 8iR6M070pq8ZM1XJhXeBkBHEdat1YkeQ2N3js2w/+qUoxYNJXOQbOjfYYHsNw3K72L8t i9HuEc/IeYw0cnxOLQeB4+TlFSjNlygUoQ/gkWIY9/bEFIth0C/ovyYyAmuW1sWvqZ7p Lo0j5n3+v5n+4prx6E0vXnPTkb9MAV0eDIBR7/eVmrtIqE+kIJIHdvwZ3uT8nWHfkXrG KpjeJxZGpYMt+xHt5M4B8iFv6Qch0rexXFkArtwTIhCj6P4XDdWvz5cGy1Lrj+vOHQke 9IPg== X-Original-Authentication-Results: mx.google.com; spf=pass (google.com: domain of nitesh@redhat.com designates 209.132.183.28 as permitted sender) smtp.mailfrom=nitesh@redhat.com; dmarc=pass (p=NONE sp=NONE dis=NONE) header.from=redhat.com X-Gm-Message-State: APjAAAVMehI+AH25wu9IohWKsUUOw9pWw5AkFIqbeAJDLH5+vkFZhYGS D+H/tkRjtsvR2Odpv1LDNXbSyW+PTnRwuALEWhpixNgznFcSmMjoKLOYsoTbuIEBxOQX7xyyHWA GUKiCGyVRYnSP2sK23UO/tS9ppeZIB954SHTsHxY5skVCTdbYpG1co/kwAjHeDz2tZA== X-Received: by 2002:a37:657:: with SMTP id 84mr14551515qkg.86.1552072242572; Fri, 08 Mar 2019 11:10:42 -0800 (PST) X-Google-Smtp-Source: APXvYqwYYPctBL/jBuQJ4o+5RhPSRFf6D3eOgfYviSMB2Q9yxiztqeP3s23LOHR5WbL2XLPm7moT X-Received: by 2002:a37:657:: with SMTP id 84mr14551465qkg.86.1552072241502; Fri, 08 Mar 2019 11:10:41 -0800 (PST) ARC-Seal: i=1; a=rsa-sha256; t=1552072241; cv=none; d=google.com; s=arc-20160816; b=nr0cYzkdwFC9RhQlszvUkxmKACuOtAwh6Fn8U85wugluqiKNaITmwnklXk4WlkZz75 Ts3qixg3jkTw2xBg/3rQYlXRZuxo29qLHc30gnPcPXaTOYyqu2qxTpHqTf8MVp3yRCv9 xI4jzQtb7M7OifajZIbK8CyonDLloBJSdSzoULxf/Qr42n3anmYseIuiH6hzx9f04XHL PwLKBRaHPs+6h5YlANjm40ybTx5ZSMKdpoNuf6pt/4HiyaG1TOgPAqxx3LV6Ywhbgw0N JyMDQiACWri2+8jOBAscVYcwUTus+14U+FIM0kVopfDVN9yZ/DgCo9/nSh3a70Bahpvx 7B2A== ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=arc-20160816; h=in-reply-to:mime-version:user-agent:date:message-id:organization :autocrypt:openpgp:from:references:cc:to:subject; bh=FMBr24ynMW9XPu7VBssYQrMAzHMlm70SAIn8+HmMO90=; b=nv/L8rRgOVKdO4da702QRfEu5kgfySGqMlYoIlyu+UCZsNHcYfOk25aMLGBEIyC6ot BQJijDzwgRg+Kr/cZ34D6dF0uNGb0kaJZLy8gqa7B+gXtvmeLA4/ALhp7Wlt2jt+7/4F eeJGpd6cCkdm4NgncUeDWW0ihZ7NGGQWj0UTHihL+LWFuiE9pczt9X43kF8hFoBU+nnY EJ5JXXAPkXlremQV29O9WG+EhGFn2bBvoU2hZMxl873Y/gUaoJ5VYmx9mYL7yoZW1gJC grOTmYFgYb3H8XWPgMuPL0UDzopcDX4j9e2wyitXHfHXZL6Nhc5v7Lh0K8JcUaEcHLQc aqMg== ARC-Authentication-Results: i=1; mx.google.com; spf=pass (google.com: domain of nitesh@redhat.com designates 209.132.183.28 as permitted sender) smtp.mailfrom=nitesh@redhat.com; dmarc=pass (p=NONE sp=NONE dis=NONE) header.from=redhat.com Received: from mx1.redhat.com (mx1.redhat.com. [209.132.183.28]) by mx.google.com with ESMTPS id o35si616807qvf.8.2019.03.08.11.10.41 for (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Fri, 08 Mar 2019 11:10:41 -0800 (PST) Received-SPF: pass (google.com: domain of nitesh@redhat.com designates 209.132.183.28 as permitted sender) client-ip=209.132.183.28; Authentication-Results: mx.google.com; spf=pass (google.com: domain of nitesh@redhat.com designates 209.132.183.28 as permitted sender) smtp.mailfrom=nitesh@redhat.com; dmarc=pass (p=NONE sp=NONE dis=NONE) header.from=redhat.com Received: from smtp.corp.redhat.com (int-mx07.intmail.prod.int.phx2.redhat.com [10.5.11.22]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mx1.redhat.com (Postfix) with ESMTPS id 9E056C04D29A; Fri, 8 Mar 2019 19:10:40 +0000 (UTC) Received: from [10.40.205.251] (unknown [10.40.205.251]) by smtp.corp.redhat.com (Postfix) with ESMTPS id 33CCE1001DD4; Fri, 8 Mar 2019 19:10:23 +0000 (UTC) Subject: Re: [RFC][Patch v9 2/6] KVM: Enables the kernel to isolate guest free pages To: Alexander Duyck , "Michael S. Tsirkin" Cc: David Hildenbrand , kvm list , LKML , linux-mm , Paolo Bonzini , lcapitulino@redhat.com, pagupta@redhat.com, wei.w.wang@intel.com, Yang Zhang , Rik van Riel , dodgen@google.com, Konrad Rzeszutek Wilk , dhildenb@redhat.com, Andrea Arcangeli References: <20190306155048.12868-1-nitesh@redhat.com> <20190306155048.12868-3-nitesh@redhat.com> <2d9ae889-a9b9-7969-4455-ff36944f388b@redhat.com> <22e4b1cd-38a5-6642-8cbe-d68e4fcbb0b7@redhat.com> <78b604be-2129-a716-a7a6-f5b382c9fb9c@redhat.com> <20190307212845-mutt-send-email-mst@kernel.org> From: Nitesh Narayan Lal Openpgp: preference=signencrypt Autocrypt: addr=nitesh@redhat.com; prefer-encrypt=mutual; keydata= mQINBFl4pQoBEADT/nXR2JOfsCjDgYmE2qonSGjkM1g8S6p9UWD+bf7YEAYYYzZsLtbilFTe z4nL4AV6VJmC7dBIlTi3Mj2eymD/2dkKP6UXlliWkq67feVg1KG+4UIp89lFW7v5Y8Muw3Fm uQbFvxyhN8n3tmhRe+ScWsndSBDxYOZgkbCSIfNPdZrHcnOLfA7xMJZeRCjqUpwhIjxQdFA7 n0s0KZ2cHIsemtBM8b2WXSQG9CjqAJHVkDhrBWKThDRF7k80oiJdEQlTEiVhaEDURXq+2XmG jpCnvRQDb28EJSsQlNEAzwzHMeplddfB0vCg9fRk/kOBMDBtGsTvNT9OYUZD+7jaf0gvBvBB lbKmmMMX7uJB+ejY7bnw6ePNrVPErWyfHzR5WYrIFUtgoR3LigKnw5apzc7UIV9G8uiIcZEn C+QJCK43jgnkPcSmwVPztcrkbC84g1K5v2Dxh9amXKLBA1/i+CAY8JWMTepsFohIFMXNLj+B RJoOcR4HGYXZ6CAJa3Glu3mCmYqHTOKwezJTAvmsCLd3W7WxOGF8BbBjVaPjcZfavOvkin0u DaFvhAmrzN6lL0msY17JCZo046z8oAqkyvEflFbC0S1R/POzehKrzQ1RFRD3/YzzlhmIowkM BpTqNBeHEzQAlIhQuyu1ugmQtfsYYq6FPmWMRfFPes/4JUU/PQARAQABtCVOaXRlc2ggTmFy YXlhbiBMYWwgPG5pbGFsQHJlZGhhdC5jb20+iQI9BBMBCAAnBQJZeKUKAhsjBQkJZgGABQsJ CAcCBhUICQoLAgQWAgMBAh4BAheAAAoJEKOGQNwGMqM56lEP/A2KMs/pu0URcVk/kqVwcBhU SnvB8DP3lDWDnmVrAkFEOnPX7GTbactQ41wF/xwjwmEmTzLrMRZpkqz2y9mV0hWHjqoXbOCS 6RwK3ri5e2ThIPoGxFLt6TrMHgCRwm8YuOSJ97o+uohCTN8pmQ86KMUrDNwMqRkeTRW9wWIQ EdDqW44VwelnyPwcmWHBNNb1Kd8j3xKlHtnS45vc6WuoKxYRBTQOwI/5uFpDZtZ1a5kq9Ak/ MOPDDZpd84rqd+IvgMw5z4a5QlkvOTpScD21G3gjmtTEtyfahltyDK/5i8IaQC3YiXJCrqxE r7/4JMZeOYiKpE9iZMtS90t4wBgbVTqAGH1nE/ifZVAUcCtycD0f3egX9CHe45Ad4fsF3edQ ESa5tZAogiA4Hc/yQpnnf43a3aQ67XPOJXxS0Qptzu4vfF9h7kTKYWSrVesOU3QKYbjEAf95 NewF9FhAlYqYrwIwnuAZ8TdXVDYt7Z3z506//sf6zoRwYIDA8RDqFGRuPMXUsoUnf/KKPrtR ceLcSUP/JCNiYbf1/QtW8S6Ca/4qJFXQHp0knqJPGmwuFHsarSdpvZQ9qpxD3FnuPyo64S2N Dfq8TAeifNp2pAmPY2PAHQ3nOmKgMG8Gn5QiORvMUGzSz8Lo31LW58NdBKbh6bci5+t/HE0H pnyVf5xhNC/FuQINBFl4pQoBEACr+MgxWHUP76oNNYjRiNDhaIVtnPRqxiZ9v4H5FPxJy9UD Bqr54rifr1E+K+yYNPt/Po43vVL2cAyfyI/LVLlhiY4yH6T1n+Di/hSkkviCaf13gczuvgz4 KVYLwojU8+naJUsiCJw01MjO3pg9GQ+47HgsnRjCdNmmHiUQqksMIfd8k3reO9SUNlEmDDNB XuSzkHjE5y/R/6p8uXaVpiKPfHoULjNRWaFc3d2JGmxJpBdpYnajoz61m7XJlgwl/B5Ql/6B dHGaX3VHxOZsfRfugwYF9CkrPbyO5PK7yJ5vaiWre7aQ9bmCtXAomvF1q3/qRwZp77k6i9R3 tWfXjZDOQokw0u6d6DYJ0Vkfcwheg2i/Mf/epQl7Pf846G3PgSnyVK6cRwerBl5a68w7xqVU 4KgAh0DePjtDcbcXsKRT9D63cfyfrNE+ea4i0SVik6+N4nAj1HbzWHTk2KIxTsJXypibOKFX 2VykltxutR1sUfZBYMkfU4PogE7NjVEU7KtuCOSAkYzIWrZNEQrxYkxHLJsWruhSYNRsqVBy KvY6JAsq/i5yhVd5JKKU8wIOgSwC9P6mXYRgwPyfg15GZpnw+Fpey4bCDkT5fMOaCcS+vSU1 UaFmC4Ogzpe2BW2DOaPU5Ik99zUFNn6cRmOOXArrryjFlLT5oSOe4IposgWzdwARAQABiQIl BBgBCAAPBQJZeKUKAhsMBQkJZgGAAAoJEKOGQNwGMqM5ELoP/jj9d9gF1Al4+9bngUlYohYu 0sxyZo9IZ7Yb7cHuJzOMqfgoP4tydP4QCuyd9Q2OHHL5AL4VFNb8SvqAxxYSPuDJTI3JZwI7 d8JTPKwpulMSUaJE8ZH9n8A/+sdC3CAD4QafVBcCcbFe1jifHmQRdDrvHV9Es14QVAOTZhnJ vweENyHEIxkpLsyUUDuVypIo6y/Cws+EBCWt27BJi9GH/EOTB0wb+2ghCs/i3h8a+bi+bS7L FCCm/AxIqxRurh2UySn0P/2+2eZvneJ1/uTgfxnjeSlwQJ1BWzMAdAHQO1/lnbyZgEZEtUZJ x9d9ASekTtJjBMKJXAw7GbB2dAA/QmbA+Q+Xuamzm/1imigz6L6sOt2n/X/SSc33w8RJUyor SvAIoG/zU2Y76pKTgbpQqMDmkmNYFMLcAukpvC4ki3Sf086TdMgkjqtnpTkEElMSFJC8npXv 3QnGGOIfFug/qs8z03DLPBz9VYS26jiiN7QIJVpeeEdN/LKnaz5LO+h5kNAyj44qdF2T2AiF HxnZnxO5JNP5uISQH3FjxxGxJkdJ8jKzZV7aT37sC+Rp0o3KNc+GXTR+GSVq87Xfuhx0LRST NK9ZhT0+qkiN7npFLtNtbzwqaqceq3XhafmCiw8xrtzCnlB/C4SiBr/93Ip4kihXJ0EuHSLn VujM7c/b4pps Organization: Red Hat Inc, Message-ID: <17d2afa6-556e-ec73-40dc-beac536b3f20@redhat.com> Date: Fri, 8 Mar 2019 14:10:20 -0500 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:60.0) Gecko/20100101 Thunderbird/60.4.0 MIME-Version: 1.0 In-Reply-To: Content-Type: multipart/signed; micalg=pgp-sha256; protocol="application/pgp-signature"; boundary="xD6yFrm8IWkNhOHZM6MlHlwxr5wIiR1nl" X-Scanned-By: MIMEDefang 2.84 on 10.5.11.22 X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-4.5.16 (mx1.redhat.com [10.5.110.31]); Fri, 08 Mar 2019 19:10:40 +0000 (UTC) X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: This is an OpenPGP/MIME signed message (RFC 4880 and 3156) --xD6yFrm8IWkNhOHZM6MlHlwxr5wIiR1nl Content-Type: multipart/mixed; boundary="dufyYFqOkdVSep0QbzK5h22WftvV2Qan2"; protected-headers="v1" From: Nitesh Narayan Lal To: Alexander Duyck , "Michael S. Tsirkin" Cc: David Hildenbrand , kvm list , LKML , linux-mm , Paolo Bonzini , lcapitulino@redhat.com, pagupta@redhat.com, wei.w.wang@intel.com, Yang Zhang , Rik van Riel , dodgen@google.com, Konrad Rzeszutek Wilk , dhildenb@redhat.com, Andrea Arcangeli Message-ID: <17d2afa6-556e-ec73-40dc-beac536b3f20@redhat.com> Subject: Re: [RFC][Patch v9 2/6] KVM: Enables the kernel to isolate guest free pages References: <20190306155048.12868-1-nitesh@redhat.com> <20190306155048.12868-3-nitesh@redhat.com> <2d9ae889-a9b9-7969-4455-ff36944f388b@redhat.com> <22e4b1cd-38a5-6642-8cbe-d68e4fcbb0b7@redhat.com> <78b604be-2129-a716-a7a6-f5b382c9fb9c@redhat.com> <20190307212845-mutt-send-email-mst@kernel.org> In-Reply-To: --dufyYFqOkdVSep0QbzK5h22WftvV2Qan2 Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: quoted-printable Content-Language: en-US On 3/8/19 1:06 PM, Alexander Duyck wrote: > On Thu, Mar 7, 2019 at 6:32 PM Michael S. Tsirkin wrot= e: >> On Thu, Mar 07, 2019 at 02:35:53PM -0800, Alexander Duyck wrote: >>> The only other thing I still want to try and see if I can do is to ad= d >>> a jiffies value to the page private data in the case of the buddy >>> pages. >> Actually there's one extra thing I think we should do, and that is mak= e >> sure we do not leave less than X% off the free memory at a time. >> This way chances of triggering an OOM are lower. > If nothing else we could probably look at doing a watermark of some > sort so we have to have X amount of memory free but not hinted before > we will start providing the hints. It would just be a matter of > tracking how much memory we have hinted on versus the amount of memory > that has been pulled from that pool. This is to avoid false OOM in the guest? > It is another reason why we > probably want a bit in the buddy pages somewhere to indicate if a page > has been hinted or not as we can then use that to determine if we have > to account for it in the statistics. The one benefit which I can see of having an explicit bit is that it will help us to have a single hook away from the hot path within buddy merging code (just like your arch_merge_page) and still avoid duplicate hints while releasing pages. I still have to check PG_idle and PG_young which you mentioned but I don't think we can reuse any existing bits. If we really want to have something like a watermark, then can't we use zone->free_pages before isolating to see how many free pages are there and put a threshold on it? (__isolate_free_page() does a similar thing but it does that on per request basis). > >>> With that we could track the age of the page so it becomes >>> easier to only target pages that are truly going cold rather than >>> trying to grab pages that were added to the freelist recently. >> I like that but I have a vague memory of discussing this with Rik van >> Riel and him saying it's actually better to take away recently used >> ones. Can't see why would that be but maybe I remember wrong. Rik - am= I >> just confused? > It is probably to cut down on the need for disk writes in the case of > swap. If that is the case it ends up being a trade off. > > The sooner we hint the less likely it is that we will need to write a > given page to disk. However the sooner we hint, the more likely it is > we will need to trigger a page fault and pull back in a zero page to > populate the last page we were working on. The sweet spot will be that > period of time that is somewhere in between so we don't trigger > unnecessary page faults and we don't need to perform additional swap > reads/writes. --=20 Regards Nitesh --dufyYFqOkdVSep0QbzK5h22WftvV2Qan2-- --xD6yFrm8IWkNhOHZM6MlHlwxr5wIiR1nl Content-Type: application/pgp-signature; name="signature.asc" Content-Description: OpenPGP digital signature Content-Disposition: attachment; filename="signature.asc" -----BEGIN PGP SIGNATURE----- iQIzBAEBCAAdFiEEkXcoRVGaqvbHPuAGo4ZA3AYyozkFAlyCvhwACgkQo4ZA3AYy ozklHg//U4m8Ze127fvPDuSxHHYFcioTxdYLp2hdRLjhbWE4Oe+dBBHYmh53nkzq wWcMhfbDNBDBf1wYcPLEK+i1Hrf0GXyzAFd0XO0W8tOcv4AQi+q7KtZR9ieMaLyo sqxAlflvm+Vn6o89L+6mLW/l/xh/83J6GJjwETBvogCX/z84wx+AaZ4Iq5aV561P h7OpQJdyywMMRE8PRvh3kYGppGqLZ5kDtCbbC4QVOjXM8Hzu40MqJzrqU2rndPHo qOv4cIIBLxmS4nX288aRKSBr9Y6HDs1KnUv8gjwSA6yW0wd5SnZE4CrR4ERNmXc0 KqNABQdpyZI1lEoao8Cf6yGnrPKUmV7Md7NwldWYOiE7/2Oy8AlDJG6xWywU+nHV mgumckUeZiOd7gr8ZLX1W+GlVafa4Sxj8s87rLgaAeC5uyvAAIHA4XzNa3NkdJnW J3bjvxr9DlWKVJoq4n6NUG918u8FH+kdBLmHChJwwB2SN5crCYuMxeEhESGY0jGi 7UzUgF8e3gEHWcnZ4MZ3xsUyxBcFAyhzh5jHmCYqINe10sdZN4ebRqdONFebRS5v MXhRko7axTD7BW1goaaLEwEp7FY7xhNRg1JNeJUfsuWNCl2YnJiR7aobHF93jXjR 3fDCjQ5FQGdkQzkrLwIls+ycXbZ9kktcaOxEvPoU59l2XLbPSLY= =Rc9w -----END PGP SIGNATURE----- --xD6yFrm8IWkNhOHZM6MlHlwxr5wIiR1nl--