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=-6.8 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS, URIBL_BLOCKED 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 C3DD7C76191 for ; Wed, 24 Jul 2019 20:46:13 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 9B23B217F4 for ; Wed, 24 Jul 2019 20:46:13 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728761AbfGXUqM (ORCPT ); Wed, 24 Jul 2019 16:46:12 -0400 Received: from mail-qt1-f195.google.com ([209.85.160.195]:38714 "EHLO mail-qt1-f195.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726762AbfGXUqM (ORCPT ); Wed, 24 Jul 2019 16:46:12 -0400 Received: by mail-qt1-f195.google.com with SMTP id n11so46897635qtl.5 for ; Wed, 24 Jul 2019 13:46:11 -0700 (PDT) X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:date:from:to:cc:subject:message-id:references :mime-version:content-disposition:in-reply-to; bh=kEmnRIh7eb5SZPPwt0SSGdzpr7hhPeFdagIv+/tAxBM=; b=Gw0xGDVCfpuSMyl2fm340k+ukP7D53VeKuytSeB5yHAV6OK6i49TVgGh/eM28rKMFL nmM7OPaUP2HO4fhhNWuiPzrneBwdSut96RSLLfTY8Y9fd+3Q/5kYVjPXLNh4Ab8epNj/ E6fEBRpc0LG5fRvspCa2+MOPR8rEEb1ehRoQiQqEi9LlBAereURlty/k4Nvgx0jjkYsW GLE9cQqRuOhItZPspd7Se8J6Bm/aVFP6VbsCDORD0HLiXGoRqq5jSghEK97T49yoy0Tw awPmHqxTCi4M617ckBSNefki4L4HES3hHk3WHSalNWomEcCPTsBQZJUEwlKOSd1xOfdZ jLVQ== X-Gm-Message-State: APjAAAWzDTbDL7VEC0LkUCFRQasfrEsFYm8UpiQcN9wevoxY3yxaK8/W zUVKElayPRTUYa/n+/RXxqDCKQ== X-Google-Smtp-Source: APXvYqwbpIKZ55eh/98dX0EXGRSXf9HthV7sKQoo76sbcztNZu/6XKn9qDAYGtrzpMy5Z2naK3MXlQ== X-Received: by 2002:ac8:5141:: with SMTP id h1mr59926940qtn.15.1564001170693; Wed, 24 Jul 2019 13:46:10 -0700 (PDT) Received: from redhat.com (bzq-79-181-91-42.red.bezeqint.net. [79.181.91.42]) by smtp.gmail.com with ESMTPSA id c5sm29604425qta.5.2019.07.24.13.46.05 (version=TLS1_3 cipher=AEAD-AES256-GCM-SHA384 bits=256/256); Wed, 24 Jul 2019 13:46:09 -0700 (PDT) Date: Wed, 24 Jul 2019 16:46:03 -0400 From: "Michael S. Tsirkin" To: Alexander Duyck Cc: Alexander Duyck , nitesh@redhat.com, kvm@vger.kernel.org, david@redhat.com, dave.hansen@intel.com, linux-kernel@vger.kernel.org, linux-mm@kvack.org, akpm@linux-foundation.org, 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 Subject: Re: [PATCH v2 QEMU] virtio-balloon: Provide a interface for "bubble hinting" Message-ID: <20190724164433-mutt-send-email-mst@kernel.org> References: <20190724165158.6685.87228.stgit@localhost.localdomain> <20190724171050.7888.62199.stgit@localhost.localdomain> <20190724150224-mutt-send-email-mst@kernel.org> <6218af96d7d55935f2cf607d47680edc9b90816e.camel@linux.intel.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <6218af96d7d55935f2cf607d47680edc9b90816e.camel@linux.intel.com> Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Wed, Jul 24, 2019 at 01:18:00PM -0700, Alexander Duyck wrote: > On Wed, 2019-07-24 at 15:02 -0400, Michael S. Tsirkin wrote: > > On Wed, Jul 24, 2019 at 10:12:10AM -0700, Alexander Duyck wrote: > > > From: Alexander Duyck > > > > > > Add support for what I am referring to as "bubble hinting". Basically the > > > idea is to function very similar to how the balloon works in that we > > > basically end up madvising the page as not being used. However we don't > > > really need to bother with any deflate type logic since the page will be > > > faulted back into the guest when it is read or written to. > > > > > > This is meant to be a simplification of the existing balloon interface > > > to use for providing hints to what memory needs to be freed. I am assuming > > > this is safe to do as the deflate logic does not actually appear to do very > > > much other than tracking what subpages have been released and which ones > > > haven't. > > > > > > Signed-off-by: Alexander Duyck > > > --- > > > hw/virtio/virtio-balloon.c | 40 +++++++++++++++++++++++ > > > include/hw/virtio/virtio-balloon.h | 2 + > > > include/standard-headers/linux/virtio_balloon.h | 1 + > > > 3 files changed, 42 insertions(+), 1 deletion(-) > > > > > > diff --git a/hw/virtio/virtio-balloon.c b/hw/virtio/virtio-balloon.c > > > index 2112874055fb..70c0004c0f88 100644 > > > --- a/hw/virtio/virtio-balloon.c > > > +++ b/hw/virtio/virtio-balloon.c > > > @@ -328,6 +328,39 @@ static void balloon_stats_set_poll_interval(Object *obj, Visitor *v, > > > balloon_stats_change_timer(s, 0); > > > } > > > > > > +static void virtio_bubble_handle_output(VirtIODevice *vdev, VirtQueue *vq) > > > +{ > > > + VirtQueueElement *elem; > > > + > > > + while ((elem = virtqueue_pop(vq, sizeof(VirtQueueElement)))) { > > > + unsigned int i; > > > + > > > + for (i = 0; i < elem->in_num; i++) { > > > + void *addr = elem->in_sg[i].iov_base; > > > + size_t size = elem->in_sg[i].iov_len; > > > + ram_addr_t ram_offset; > > > + size_t rb_page_size; > > > + RAMBlock *rb; > > > + > > > + if (qemu_balloon_is_inhibited()) > > > + continue; > > > + > > > + rb = qemu_ram_block_from_host(addr, false, &ram_offset); > > > + rb_page_size = qemu_ram_pagesize(rb); > > > + > > > + /* For now we will simply ignore unaligned memory regions */ > > > + if ((ram_offset | size) & (rb_page_size - 1)) > > > + continue; > > > + > > > + ram_block_discard_range(rb, ram_offset, size); > > > > I suspect this needs to do like the migration type of > > hinting and get disabled if page poisoning is in effect. > > Right? > > Shouldn't something like that end up getting handled via > qemu_balloon_is_inhibited, or did I miss something there? I assumed cases > like that would end up setting qemu_balloon_is_inhibited to true, if that > isn't the case then I could add some additional conditions. I would do it > in about the same spot as the qemu_balloon_is_inhibited check. Well qemu_balloon_is_inhibited is for the regular ballooning, mostly a work-around for limitations is host linux iommu APIs when it's used with VFIO. -- MST