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=-0.8 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SPF_PASS autolearn=ham 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 BCAD8C43144 for ; Wed, 27 Jun 2018 02:56:10 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 64C7520846 for ; Wed, 27 Jun 2018 02:56:10 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 64C7520846 Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=intel.com Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=linux-kernel-owner@vger.kernel.org Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752254AbeF0C4I (ORCPT ); Tue, 26 Jun 2018 22:56:08 -0400 Received: from mga05.intel.com ([192.55.52.43]:46941 "EHLO mga05.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750962AbeF0C4G (ORCPT ); Tue, 26 Jun 2018 22:56:06 -0400 X-Amp-Result: SKIPPED(no attachment in message) X-Amp-File-Uploaded: False Received: from fmsmga003.fm.intel.com ([10.253.24.29]) by fmsmga105.fm.intel.com with ESMTP/TLS/DHE-RSA-AES256-GCM-SHA384; 26 Jun 2018 19:56:06 -0700 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.51,277,1526367600"; d="scan'208";a="60445144" Received: from unknown (HELO [10.239.13.97]) ([10.239.13.97]) by FMSMGA003.fm.intel.com with ESMTP; 26 Jun 2018 19:56:03 -0700 Message-ID: <5B32FDB5.4040506@intel.com> Date: Wed, 27 Jun 2018 11:00:05 +0800 From: Wei Wang User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:31.0) Gecko/20100101 Thunderbird/31.7.0 MIME-Version: 1.0 To: "Michael S. Tsirkin" CC: virtio-dev@lists.oasis-open.org, linux-kernel@vger.kernel.org, virtualization@lists.linux-foundation.org, kvm@vger.kernel.org, linux-mm@kvack.org, mhocko@kernel.org, akpm@linux-foundation.org, torvalds@linux-foundation.org, pbonzini@redhat.com, liliang.opensource@gmail.com, yang.zhang.wz@gmail.com, quan.xu0@gmail.com, nilal@redhat.com, riel@redhat.com, peterx@redhat.com Subject: Re: [PATCH v34 2/4] virtio-balloon: VIRTIO_BALLOON_F_FREE_PAGE_HINT References: <1529928312-30500-1-git-send-email-wei.w.wang@intel.com> <1529928312-30500-3-git-send-email-wei.w.wang@intel.com> <20180626002822-mutt-send-email-mst@kernel.org> <5B31B71B.6080709@intel.com> <20180626064338-mutt-send-email-mst@kernel.org> <5B323140.1000306@intel.com> <20180626163139-mutt-send-email-mst@kernel.org> <5B32E742.8080902@intel.com> <20180627053952-mutt-send-email-mst@kernel.org> In-Reply-To: <20180627053952-mutt-send-email-mst@kernel.org> Content-Type: text/plain; charset=windows-1252; format=flowed Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 06/27/2018 10:41 AM, Michael S. Tsirkin wrote: > On Wed, Jun 27, 2018 at 09:24:18AM +0800, Wei Wang wrote: >> On 06/26/2018 09:34 PM, Michael S. Tsirkin wrote: >>> On Tue, Jun 26, 2018 at 08:27:44PM +0800, Wei Wang wrote: >>>> On 06/26/2018 11:56 AM, Michael S. Tsirkin wrote: >>>>> On Tue, Jun 26, 2018 at 11:46:35AM +0800, Wei Wang wrote: >>>>> >>>>>>>> + if (!arrays) >>>>>>>> + return NULL; >>>>>>>> + >>>>>>>> + for (i = 0; i < max_array_num; i++) { >>>>>>> So we are getting a ton of memory here just to free it up a bit later. >>>>>>> Why doesn't get_from_free_page_list get the pages from free list for us? >>>>>>> We could also avoid the 1st allocation then - just build a list >>>>>>> of these. >>>>>> That wouldn't be a good choice for us. If we check how the regular >>>>>> allocation works, there are many many things we need to consider when pages >>>>>> are allocated to users. >>>>>> For example, we need to take care of the nr_free >>>>>> counter, we need to check the watermark and perform the related actions. >>>>>> Also the folks working on arch_alloc_page to monitor page allocation >>>>>> activities would get a surprise..if page allocation is allowed to work in >>>>>> this way. >>>>>> >>>>> mm/ code is well positioned to handle all this correctly. >>>> I'm afraid that would be a re-implementation of the alloc functions, >>> A re-factoring - you can share code. The main difference is locking. >>> >>>> and >>>> that would be much more complex than what we have. I think your idea of >>>> passing a list of pages is better. >>>> >>>> Best, >>>> Wei >>> How much memory is this allocating anyway? >>> >> For every 2TB memory that the guest has, we allocate 4MB. > Hmm I guess I'm missing something, I don't see it: > > > + max_entries = max_free_page_blocks(ARRAY_ALLOC_ORDER); > + entries_per_page = PAGE_SIZE / sizeof(__le64); > + entries_per_array = entries_per_page * (1 << ARRAY_ALLOC_ORDER); > + max_array_num = max_entries / entries_per_array + > + !!(max_entries % entries_per_array); > > Looks like you always allocate the max number? Yes. We allocated the max number and then free what's not used. For example, a 16TB guest, we allocate Four 4MB buffers and pass the 4 buffers to get_from_free_page_list. If it uses 3, then the remaining 1 "4MB buffer" will end up being freed. For today's guests, max_array_num is usually 1. Best, Wei From mboxrd@z Thu Jan 1 00:00:00 1970 From: Wei Wang Subject: Re: [PATCH v34 2/4] virtio-balloon: VIRTIO_BALLOON_F_FREE_PAGE_HINT Date: Wed, 27 Jun 2018 11:00:05 +0800 Message-ID: <5B32FDB5.4040506@intel.com> References: <1529928312-30500-1-git-send-email-wei.w.wang@intel.com> <1529928312-30500-3-git-send-email-wei.w.wang@intel.com> <20180626002822-mutt-send-email-mst@kernel.org> <5B31B71B.6080709@intel.com> <20180626064338-mutt-send-email-mst@kernel.org> <5B323140.1000306@intel.com> <20180626163139-mutt-send-email-mst@kernel.org> <5B32E742.8080902@intel.com> <20180627053952-mutt-send-email-mst@kernel.org> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii"; Format="flowed" Content-Transfer-Encoding: 7bit Cc: yang.zhang.wz@gmail.com, virtio-dev@lists.oasis-open.org, riel@redhat.com, quan.xu0@gmail.com, kvm@vger.kernel.org, nilal@redhat.com, liliang.opensource@gmail.com, linux-kernel@vger.kernel.org, mhocko@kernel.org, linux-mm@kvack.org, pbonzini@redhat.com, akpm@linux-foundation.org, virtualization@lists.linux-foundation.org, torvalds@linux-foundation.org To: "Michael S. Tsirkin" Return-path: In-Reply-To: <20180627053952-mutt-send-email-mst@kernel.org> List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: virtualization-bounces@lists.linux-foundation.org Errors-To: virtualization-bounces@lists.linux-foundation.org List-Id: kvm.vger.kernel.org On 06/27/2018 10:41 AM, Michael S. Tsirkin wrote: > On Wed, Jun 27, 2018 at 09:24:18AM +0800, Wei Wang wrote: >> On 06/26/2018 09:34 PM, Michael S. Tsirkin wrote: >>> On Tue, Jun 26, 2018 at 08:27:44PM +0800, Wei Wang wrote: >>>> On 06/26/2018 11:56 AM, Michael S. Tsirkin wrote: >>>>> On Tue, Jun 26, 2018 at 11:46:35AM +0800, Wei Wang wrote: >>>>> >>>>>>>> + if (!arrays) >>>>>>>> + return NULL; >>>>>>>> + >>>>>>>> + for (i = 0; i < max_array_num; i++) { >>>>>>> So we are getting a ton of memory here just to free it up a bit later. >>>>>>> Why doesn't get_from_free_page_list get the pages from free list for us? >>>>>>> We could also avoid the 1st allocation then - just build a list >>>>>>> of these. >>>>>> That wouldn't be a good choice for us. If we check how the regular >>>>>> allocation works, there are many many things we need to consider when pages >>>>>> are allocated to users. >>>>>> For example, we need to take care of the nr_free >>>>>> counter, we need to check the watermark and perform the related actions. >>>>>> Also the folks working on arch_alloc_page to monitor page allocation >>>>>> activities would get a surprise..if page allocation is allowed to work in >>>>>> this way. >>>>>> >>>>> mm/ code is well positioned to handle all this correctly. >>>> I'm afraid that would be a re-implementation of the alloc functions, >>> A re-factoring - you can share code. The main difference is locking. >>> >>>> and >>>> that would be much more complex than what we have. I think your idea of >>>> passing a list of pages is better. >>>> >>>> Best, >>>> Wei >>> How much memory is this allocating anyway? >>> >> For every 2TB memory that the guest has, we allocate 4MB. > Hmm I guess I'm missing something, I don't see it: > > > + max_entries = max_free_page_blocks(ARRAY_ALLOC_ORDER); > + entries_per_page = PAGE_SIZE / sizeof(__le64); > + entries_per_array = entries_per_page * (1 << ARRAY_ALLOC_ORDER); > + max_array_num = max_entries / entries_per_array + > + !!(max_entries % entries_per_array); > > Looks like you always allocate the max number? Yes. We allocated the max number and then free what's not used. For example, a 16TB guest, we allocate Four 4MB buffers and pass the 4 buffers to get_from_free_page_list. If it uses 3, then the remaining 1 "4MB buffer" will end up being freed. For today's guests, max_array_num is usually 1. Best, Wei From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: virtio-dev-return-4556-cohuck=redhat.com@lists.oasis-open.org Sender: List-Post: List-Help: List-Unsubscribe: List-Subscribe: Received: from lists.oasis-open.org (oasis-open.org [66.179.20.138]) by lists.oasis-open.org (Postfix) with ESMTP id DE310581809C for ; Tue, 26 Jun 2018 19:56:16 -0700 (PDT) Message-ID: <5B32FDB5.4040506@intel.com> Date: Wed, 27 Jun 2018 11:00:05 +0800 From: Wei Wang MIME-Version: 1.0 References: <1529928312-30500-1-git-send-email-wei.w.wang@intel.com> <1529928312-30500-3-git-send-email-wei.w.wang@intel.com> <20180626002822-mutt-send-email-mst@kernel.org> <5B31B71B.6080709@intel.com> <20180626064338-mutt-send-email-mst@kernel.org> <5B323140.1000306@intel.com> <20180626163139-mutt-send-email-mst@kernel.org> <5B32E742.8080902@intel.com> <20180627053952-mutt-send-email-mst@kernel.org> In-Reply-To: <20180627053952-mutt-send-email-mst@kernel.org> Content-Type: text/plain; charset=windows-1252; format=flowed Content-Transfer-Encoding: 7bit Subject: [virtio-dev] Re: [PATCH v34 2/4] virtio-balloon: VIRTIO_BALLOON_F_FREE_PAGE_HINT To: "Michael S. Tsirkin" Cc: virtio-dev@lists.oasis-open.org, linux-kernel@vger.kernel.org, virtualization@lists.linux-foundation.org, kvm@vger.kernel.org, linux-mm@kvack.org, mhocko@kernel.org, akpm@linux-foundation.org, torvalds@linux-foundation.org, pbonzini@redhat.com, liliang.opensource@gmail.com, yang.zhang.wz@gmail.com, quan.xu0@gmail.com, nilal@redhat.com, riel@redhat.com, peterx@redhat.com List-ID: On 06/27/2018 10:41 AM, Michael S. Tsirkin wrote: > On Wed, Jun 27, 2018 at 09:24:18AM +0800, Wei Wang wrote: >> On 06/26/2018 09:34 PM, Michael S. Tsirkin wrote: >>> On Tue, Jun 26, 2018 at 08:27:44PM +0800, Wei Wang wrote: >>>> On 06/26/2018 11:56 AM, Michael S. Tsirkin wrote: >>>>> On Tue, Jun 26, 2018 at 11:46:35AM +0800, Wei Wang wrote: >>>>> >>>>>>>> + if (!arrays) >>>>>>>> + return NULL; >>>>>>>> + >>>>>>>> + for (i = 0; i < max_array_num; i++) { >>>>>>> So we are getting a ton of memory here just to free it up a bit later. >>>>>>> Why doesn't get_from_free_page_list get the pages from free list for us? >>>>>>> We could also avoid the 1st allocation then - just build a list >>>>>>> of these. >>>>>> That wouldn't be a good choice for us. If we check how the regular >>>>>> allocation works, there are many many things we need to consider when pages >>>>>> are allocated to users. >>>>>> For example, we need to take care of the nr_free >>>>>> counter, we need to check the watermark and perform the related actions. >>>>>> Also the folks working on arch_alloc_page to monitor page allocation >>>>>> activities would get a surprise..if page allocation is allowed to work in >>>>>> this way. >>>>>> >>>>> mm/ code is well positioned to handle all this correctly. >>>> I'm afraid that would be a re-implementation of the alloc functions, >>> A re-factoring - you can share code. The main difference is locking. >>> >>>> and >>>> that would be much more complex than what we have. I think your idea of >>>> passing a list of pages is better. >>>> >>>> Best, >>>> Wei >>> How much memory is this allocating anyway? >>> >> For every 2TB memory that the guest has, we allocate 4MB. > Hmm I guess I'm missing something, I don't see it: > > > + max_entries = max_free_page_blocks(ARRAY_ALLOC_ORDER); > + entries_per_page = PAGE_SIZE / sizeof(__le64); > + entries_per_array = entries_per_page * (1 << ARRAY_ALLOC_ORDER); > + max_array_num = max_entries / entries_per_array + > + !!(max_entries % entries_per_array); > > Looks like you always allocate the max number? Yes. We allocated the max number and then free what's not used. For example, a 16TB guest, we allocate Four 4MB buffers and pass the 4 buffers to get_from_free_page_list. If it uses 3, then the remaining 1 "4MB buffer" will end up being freed. For today's guests, max_array_num is usually 1. Best, Wei --------------------------------------------------------------------- To unsubscribe, e-mail: virtio-dev-unsubscribe@lists.oasis-open.org For additional commands, e-mail: virtio-dev-help@lists.oasis-open.org