Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S933490AbcJZPrx (ORCPT ); Wed, 26 Oct 2016 11:47:53 -0400 Received: from mx1.redhat.com ([209.132.183.28]:59578 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S932174AbcJZPrw (ORCPT ); Wed, 26 Oct 2016 11:47:52 -0400 Date: Wed, 26 Oct 2016 18:35:54 +0300 From: "Michael S. Tsirkin" To: Liang Li Cc: linux-kernel@vger.kernel.org, virtualization@lists.linux-foundation.org, linux-mm@kvack.org, virtio-dev@lists.oasis-open.org, kvm@vger.kernel.org, qemu-devel@nongnu.org, quintela@redhat.com, dgilbert@redhat.com, dave.hansen@intel.com, pbonzini@redhat.com, cornelia.huck@de.ibm.com, amit.shah@redhat.com Subject: Re: [RESEND PATCH v3 kernel 2/7] virtio-balloon: define new feature bit and page bitmap head Message-ID: <20161026162123-mutt-send-email-mst@kernel.org> References: <1477031080-12616-1-git-send-email-liang.z.li@intel.com> <1477031080-12616-3-git-send-email-liang.z.li@intel.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <1477031080-12616-3-git-send-email-liang.z.li@intel.com> X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-4.5.16 (mx1.redhat.com [10.5.110.25]); Wed, 26 Oct 2016 15:35:57 +0000 (UTC) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2246 Lines: 74 On Fri, Oct 21, 2016 at 02:24:35PM +0800, Liang Li wrote: > Add a new feature which supports sending the page information with > a bitmap. The current implementation uses PFNs array, which is not > very efficient. Using bitmap can improve the performance of > inflating/deflating significantly > > The page bitmap header will used to tell the host some information > about the page bitmap. e.g. the page size, page bitmap length and > start pfn. > > Signed-off-by: Liang Li > Cc: Michael S. Tsirkin > Cc: Paolo Bonzini > Cc: Cornelia Huck > Cc: Amit Shah > --- > include/uapi/linux/virtio_balloon.h | 19 +++++++++++++++++++ > 1 file changed, 19 insertions(+) > > diff --git a/include/uapi/linux/virtio_balloon.h b/include/uapi/linux/virtio_balloon.h > index 343d7dd..d3b182a 100644 > --- a/include/uapi/linux/virtio_balloon.h > +++ b/include/uapi/linux/virtio_balloon.h > @@ -34,6 +34,7 @@ > #define VIRTIO_BALLOON_F_MUST_TELL_HOST 0 /* Tell before reclaiming pages */ > #define VIRTIO_BALLOON_F_STATS_VQ 1 /* Memory Stats virtqueue */ > #define VIRTIO_BALLOON_F_DEFLATE_ON_OOM 2 /* Deflate balloon on OOM */ > +#define VIRTIO_BALLOON_F_PAGE_BITMAP 3 /* Send page info with bitmap */ > > /* Size of a PFN in the balloon interface. */ > #define VIRTIO_BALLOON_PFN_SHIFT 12 > @@ -82,4 +83,22 @@ struct virtio_balloon_stat { > __virtio64 val; > } __attribute__((packed)); > > +/* Page bitmap header structure */ > +struct balloon_bmap_hdr { Should be virtio_balloon. > + /* Used to distinguish different request */ different requests? what are the legal values? > + __virtio16 cmd; > + /* Shift width of page in the bitmap */ In which units? > + __virtio16 page_shift; > + /* flag used to identify different status */ this comment does not seem to add any value. > + __virtio16 flag; > + /* Reserved */ this too > + __virtio16 reserved; > + /* ID of the request */ > + __virtio64 req_id; > + /* The pfn of 0 bit in the bitmap */ > + __virtio64 start_pfn; > + /* The length of the bitmap, in bytes */ Why not in bits? > + __virtio64 bmap_len; > +}; > + > #endif /* _LINUX_VIRTIO_BALLOON_H */ > -- > 1.8.3.1