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=-2.3 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,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 3497EC76186 for ; Wed, 24 Jul 2019 20:38:12 +0000 (UTC) Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by mail.kernel.org (Postfix) with ESMTP id D8AAE21734 for ; Wed, 24 Jul 2019 20:38:11 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org D8AAE21734 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 7BFE08E0008; Wed, 24 Jul 2019 16:38:11 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id 76FE38E0002; Wed, 24 Jul 2019 16:38:11 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 638498E0008; Wed, 24 Jul 2019 16:38:11 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from mail-qk1-f198.google.com (mail-qk1-f198.google.com [209.85.222.198]) by kanga.kvack.org (Postfix) with ESMTP id 42A1B8E0002 for ; Wed, 24 Jul 2019 16:38:11 -0400 (EDT) Received: by mail-qk1-f198.google.com with SMTP id z13so40415978qka.15 for ; Wed, 24 Jul 2019 13:38:11 -0700 (PDT) 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:content-transfer-encoding :content-language; bh=2JDH3UtR2HjuTombjhLX9H5TW9TH6O8Ji3nipFtNjFc=; b=tnwxlzYMPLIoivA7Q/21QlFzRp6LbZacKolUxclUADVOS/GmCYrnJpsT5T+n2gDPRp tqLPkeMwRTea02A/R1YTQ8JkZCf8Ws57grJ+F4Vv5LdYtDU7aFhzIC/QwHFej4rAajiS zcZJd7wQbIK4OWBKSGOrfZ/0Pslp+JJwQwWIVoC3phCdZvxYPnI44jAV2rsxwzlixRw+ d6dvMG6xm6d4p+M4E8m4bYrl1q7QV42r28qe9kIq9J1wsERfozq1A7NioEXjZhfi7Syn WdBWTUIEKw+P2bpKgFNm9xiM5wsMLeKayyRwFMbnC+U1Jys94DmUz7E8dZrXsJ4WBtcW CUlg== 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: APjAAAVQsTNtnyS/7+ORenr6CGlnMgiP7jMIuvUe9MeJgkH94t4o3O/+ O6GNxpQ8QARhoAB/HW+WuaONZ4HlplJEYTw6AnnPMg4xkDAz0Q7e2KiZl88UCdgFPSx2K4CWCcm nJmuIz56IEbeipe1Bz46jO1IoUm29QUSh/gdMHb7SckHVe+WP5Na/734OHBrtZRd/Wg== X-Received: by 2002:a37:ef03:: with SMTP id j3mr8921997qkk.233.1564000690989; Wed, 24 Jul 2019 13:38:10 -0700 (PDT) X-Google-Smtp-Source: APXvYqwK8TTDB4xRVwhcigSqCk8w/YTLaqYDfPxkYT+RJRuihpHWiw4FDxwDggOGiETscpOVMyAV X-Received: by 2002:a37:ef03:: with SMTP id j3mr8921974qkk.233.1564000690200; Wed, 24 Jul 2019 13:38:10 -0700 (PDT) ARC-Seal: i=1; a=rsa-sha256; t=1564000690; cv=none; d=google.com; s=arc-20160816; b=D+cTP1rKeEyES3GqXxGtxIDKxnklPf98249nPYyg0WXi38qn/w2nCPLaNcqkS6+4Rx 2xmz0oA37XwJIiyVC4CQD1wizYGRZZJk9HdpM6WFk9x98HVu3gfaDkVouTuGNxHFdiYt a+dNzSg5LBNiKqN32I2l/E40De9q3TSmw0RBdl2bmx/Kvwt2SrSOfBmDmjxFMkDo1r5W jL77qx/8B5ISymOuL/oaUSZ+Fz3d/0ZIw+DRTjXzvDfUMM8gE9Xim8qWbnkfBym0VKxE eNxv8OhqBgAGOSPvvT8/vhzP/Zbb9svSupWpJv8pRn/2x99DFxko0CmHqDCWqRkqkWnA +e3g== ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=arc-20160816; h=content-language:content-transfer-encoding:in-reply-to:mime-version :user-agent:date:message-id:organization:autocrypt:openpgp:from :references:cc:to:subject; bh=2JDH3UtR2HjuTombjhLX9H5TW9TH6O8Ji3nipFtNjFc=; b=mDoRP4rZkUiNeDnuMcTeUqV4DPoFhikGiDw17XBmnysPzwOHAHt5IW4NdawOTaB6UT jbqyKMuOd3n1JQ8DCaqokrtnrQrEpRqOMX5bD4fSJQhiKM6+srWdez9RH6+x2Rh+gH82 Az3QSlpw1hM6YFZnoSVRH290l0jWAhd1Wl7g5O4brpkSKPvunEtifAgaXPpYyR45l/Pe 2zU/w4+b0cTtHXAbIGMGu7uoX4dod84f14ByIHlu+Kz0g9dbxSY0mvQcy19h/ga7cZM5 qfFbDbVDTz8mx04ATHmmGzMzCPzijqWbdsurqB3VM0HXqL1j1ROi2jh6SCXl68bjAo5m JBwA== 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 l4si17152564qtb.237.2019.07.24.13.38.10 for (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Wed, 24 Jul 2019 13:38:10 -0700 (PDT) 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-mx01.intmail.prod.int.phx2.redhat.com [10.5.11.11]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mx1.redhat.com (Postfix) with ESMTPS id 3626830B1AD1; Wed, 24 Jul 2019 20:38:09 +0000 (UTC) Received: from [10.18.17.163] (dhcp-17-163.bos.redhat.com [10.18.17.163]) by smtp.corp.redhat.com (Postfix) with ESMTPS id 97A2819800; Wed, 24 Jul 2019 20:38:01 +0000 (UTC) Subject: Re: [PATCH v2 0/5] mm / virtio: Provide support for page hinting To: Alexander Duyck , Alexander Duyck , kvm@vger.kernel.org, david@redhat.com, mst@redhat.com, dave.hansen@intel.com, linux-kernel@vger.kernel.org, linux-mm@kvack.org, akpm@linux-foundation.org Cc: yang.zhang.wz@gmail.com, pagupta@redhat.com, riel@surriel.com, konrad.wilk@oracle.com, lcapitulino@redhat.com, wei.w.wang@intel.com, aarcange@redhat.com, pbonzini@redhat.com, dan.j.williams@intel.com References: <20190724165158.6685.87228.stgit@localhost.localdomain> <0c520470-4654-cdf2-cf4d-d7c351d25e8b@redhat.com> <088abe33117e891dd6265179f678847bd574c744.camel@linux.intel.com> 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: Date: Wed, 24 Jul 2019 16:38:00 -0400 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:60.0) Gecko/20100101 Thunderbird/60.6.1 MIME-Version: 1.0 In-Reply-To: <088abe33117e891dd6265179f678847bd574c744.camel@linux.intel.com> Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: quoted-printable Content-Language: en-US X-Scanned-By: MIMEDefang 2.79 on 10.5.11.11 X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-4.5.16 (mx1.redhat.com [10.5.110.41]); Wed, 24 Jul 2019 20:38:09 +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: On 7/24/19 4:27 PM, Alexander Duyck wrote: > On Wed, 2019-07-24 at 14:40 -0400, Nitesh Narayan Lal wrote: >> On 7/24/19 12:54 PM, Alexander Duyck wrote: >>> This series provides an asynchronous means of hinting to a hypervisor= >>> that a guest page is no longer in use and can have the data associate= d >>> with it dropped. To do this I have implemented functionality that all= ows >>> for what I am referring to as page hinting >>> >>> The functionality for this is fairly simple. When enabled it will all= ocate >>> statistics to track the number of hinted pages in a given free area. = When >>> the number of free pages exceeds this value plus a high water value, >>> currently 32, >> Shouldn't we configure this to a lower number such as 16? > Yes, we could do 16. > >>> it will begin performing page hinting which consists of >>> pulling pages off of free list and placing them into a scatter list. = The >>> scatterlist is then given to the page hinting device and it will perf= orm >>> the required action to make the pages "hinted", in the case of >>> virtio-balloon this results in the pages being madvised as MADV_DONTN= EED >>> and as such they are forced out of the guest. After this they are pla= ced >>> back on the free list, and an additional bit is added if they are not= >>> merged indicating that they are a hinted buddy page instead of a stan= dard >>> buddy page. The cycle then repeats with additional non-hinted pages b= eing >>> pulled until the free areas all consist of hinted pages. >>> >>> I am leaving a number of things hard-coded such as limiting the lowes= t >>> order processed to PAGEBLOCK_ORDER, >> Have you considered making this option configurable at the compile tim= e? > We could. However, PAGEBLOCK_ORDER is already configurable on some > architectures. I didn't see much point in making it configurable in the= > case of x86 as there are only really 2 orders that this could be used i= n > that provided good performance and that MAX_ORDER - 1 and PAGEBLOCK_ORD= ER. > >>> and have left it up to the guest to >>> determine what the limit is on how many pages it wants to allocate to= >>> process the hints. >> It might make sense to set the number of pages to be hinted at a time = from the >> hypervisor. > We could do that. Although I would still want some upper limit on that = as > I would prefer to keep the high water mark as a static value since it i= s > used in an inline function. Currently the virtio driver is the one > defining the capacity of pages per request. For the upper limit I think we can rely on max vq size. Isn't? > >>> My primary testing has just been to verify the memory is being freed = after >>> allocation by running memhog 79g on a 80g guest and watching the tota= l >>> free memory via /proc/meminfo on the host. With this I have verified = most >>> of the memory is freed after each iteration. As far as performance I = have >>> been mainly focusing on the will-it-scale/page_fault1 test running wi= th >>> 16 vcpus. With that I have seen at most a 2% difference between the b= ase >>> kernel without these patches and the patches with virtio-balloon disa= bled. >>> With the patches and virtio-balloon enabled with hinting the results >>> largely depend on the host kernel. On a 3.10 RHEL kernel I saw up to = a 2% >>> drop in performance as I approached 16 threads, >> I think this is acceptable. >>> however on the the lastest >>> linux-next kernel I saw roughly a 4% to 5% improvement in performance= for >>> all tests with 8 or more threads.=20 >> Do you mean that with your patches the will-it-scale/page_fault1 numbe= rs were >> better by 4-5% over an unmodified kernel? > Yes. That is the odd thing. I am wondering if there was some improvemen= t > in the zeroing of THP pages or something that is somehow improving the > cache performance for the accessing of the pages by the test in the gue= st. The values you were observing on an unmodified kernel, were they consiste= nt over fresh reboot? Do you have any sort of workload running in the host as that could also i= mpact the numbers. > >>> I believe the difference seen is due to >>> the overhead for faulting pages back into the guest and zeroing of me= mory. >> It may also make sense to test these patches with netperf to observe h= ow much >> performance drop it is introducing. > Do you have some test you were already using? I ask because I am not su= re > netperf would generate a large enough memory window size to really trig= ger > much of a change in terms of hinting. If you have some test in mind I > could probably set it up and run it pretty quick. Earlier I have tried running netperf on a guest with 2 cores, i.e., netse= rver pinned to one and netperf running on the other. You have to specify a really large packet size and run the test for at le= ast 15-30 minutes to actually see some hinting work. > >>> Patch 4 is a bit on the large side at about 600 lines of change, howe= ver >>> I really didn't see a good way to break it up since each piece feeds = into >>> the next. So I couldn't add the statistics by themselves as it didn't= >>> really make sense to add them without something that will either read= or >>> increment/decrement them, or add the Hinted state without something t= hat >>> would set/unset it. As such I just ended up adding the entire thing a= s >>> one patch. It makes it a bit bigger but avoids the issues in the prev= ious >>> set where I was referencing things before they had been added. >>> >>> Changes from the RFC: >>> https://lore.kernel.org/lkml/20190530215223.13974.22445.stgit@localho= st.localdomain/ >>> Moved aeration requested flag out of aerator and into zone->flags. >>> Moved bounary out of free_area and into local variables for aeration.= >>> Moved aeration cycle out of interrupt and into workqueue. >>> Left nr_free as total pages instead of splitting it between raw and a= erated. >>> Combined size and physical address values in virtio ring into one 64b= value. >>> >>> Changes from v1: >>> https://lore.kernel.org/lkml/20190619222922.1231.27432.stgit@localhos= t.localdomain/ >>> Dropped "waste page treatment" in favor of "page hinting" >> We may still have to try and find a better name for virtio-balloon sid= e changes. >> As "FREE_PAGE_HINT" and "PAGE_HINTING" are still confusing. > We just need to settle on a name. Essentially all this requires is just= a > quick find and replace with whatever name we decide on. I agree. --=20 Thanks Nitesh