From mboxrd@z Thu Jan 1 00:00:00 1970 From: Anthony Liguori Subject: Re: [PATCH] virtio-balloon: Change balloon page size to 1MB Date: Tue, 21 Feb 2012 17:03:09 -0600 Message-ID: <4F4422AD.5010906@codemonkey.ws> References: <1329759269-2568-1-git-send-email-prasadjoshi.linux@gmail.com> <1329759269-2568-2-git-send-email-prasadjoshi.linux@gmail.com> Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Cc: amit.shah@redhat.com, kvm@vger.kernel.org, avi@redhat.com To: Prasad Joshi Return-path: Received: from mail-pw0-f46.google.com ([209.85.160.46]:50438 "EHLO mail-pw0-f46.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755070Ab2BUXDP (ORCPT ); Tue, 21 Feb 2012 18:03:15 -0500 Received: by pbcun15 with SMTP id un15so7885813pbc.19 for ; Tue, 21 Feb 2012 15:03:15 -0800 (PST) In-Reply-To: <1329759269-2568-2-git-send-email-prasadjoshi.linux@gmail.com> Sender: kvm-owner@vger.kernel.org List-ID: On 02/20/2012 11:34 AM, Prasad Joshi wrote: > Signed-off-by: Prasad Joshi This breaks compatibility with existing guests and more importantly, doesn't make any sense. There's no commit message explaining why 1MB is a better number than 4K, 2MB which I could at least understand as an alternative to 4K. Regards, Anthony Liguori > --- > drivers/virtio/virtio_balloon.c | 18 +++++++++--------- > include/linux/virtio_balloon.h | 4 +++- > 2 files changed, 12 insertions(+), 10 deletions(-) > > diff --git a/drivers/virtio/virtio_balloon.c b/drivers/virtio/virtio_balloon.c > index 95aeedf..e352448 100644 > --- a/drivers/virtio/virtio_balloon.c > +++ b/drivers/virtio/virtio_balloon.c > @@ -64,9 +64,8 @@ static u32 page_to_balloon_pfn(struct page *page) > { > unsigned long pfn = page_to_pfn(page); > > - BUILD_BUG_ON(PAGE_SHIFT< VIRTIO_BALLOON_PFN_SHIFT); > /* Convert pfn from Linux page size to balloon page size. */ > - return pfn>> (PAGE_SHIFT - VIRTIO_BALLOON_PFN_SHIFT); > + return pfn>> VIRTIO_BALLOON_PAGE_ORDER; > } > > static void balloon_ack(struct virtqueue *vq) > @@ -102,8 +101,9 @@ static void fill_balloon(struct virtio_balloon *vb, size_t num) > num = min(num, ARRAY_SIZE(vb->pfns)); > > for (vb->num_pfns = 0; vb->num_pfns< num; vb->num_pfns++) { > - struct page *page = alloc_page(GFP_HIGHUSER | __GFP_NORETRY | > - __GFP_NOMEMALLOC | __GFP_NOWARN); > + struct page *page = alloc_pages(GFP_HIGHUSER | __GFP_NORETRY | > + __GFP_NOMEMALLOC | __GFP_NOWARN, > + VIRTIO_BALLOON_PAGE_ORDER); > if (!page) { > if (printk_ratelimit()) > dev_printk(KERN_INFO,&vb->vdev->dev, > @@ -114,7 +114,7 @@ static void fill_balloon(struct virtio_balloon *vb, size_t num) > break; > } > vb->pfns[vb->num_pfns] = page_to_balloon_pfn(page); > - totalram_pages--; > + totalram_pages -= VIRTIO_BALLOON_PAGES; > vb->num_pages++; > list_add(&page->lru,&vb->pages); > } > @@ -131,8 +131,8 @@ static void release_pages_by_pfn(const u32 pfns[], unsigned int num) > unsigned int i; > > for (i = 0; i< num; i++) { > - __free_page(pfn_to_page(pfns[i])); > - totalram_pages++; > + __free_pages(pfn_to_page(pfns[i]), VIRTIO_BALLOON_PAGE_ORDER); > + totalram_pages += VIRTIO_BALLOON_PAGES; > } > } > > @@ -146,7 +146,7 @@ static void leak_balloon(struct virtio_balloon *vb, size_t num) > for (vb->num_pfns = 0; vb->num_pfns< num; vb->num_pfns++) { > page = list_first_entry(&vb->pages, struct page, lru); > list_del(&page->lru); > - vb->pfns[vb->num_pfns] = page_to_balloon_pfn(page); > + vb->pfns[vb->num_pfns] = page_to_pfn(page); > vb->num_pages--; > } > > @@ -400,7 +400,7 @@ static int virtballoon_restore(struct virtio_device *vdev) > /* We don't have these pages in the balloon anymore! */ > list_for_each_entry_safe(page, page2,&vb->pages, lru) { > list_del(&page->lru); > - totalram_pages++; > + totalram_pages += VIRTIO_BALLOON_PAGES; > } > return init_vqs(vdev->priv); > } > diff --git a/include/linux/virtio_balloon.h b/include/linux/virtio_balloon.h > index 652dc8b..86840fe 100644 > --- a/include/linux/virtio_balloon.h > +++ b/include/linux/virtio_balloon.h > @@ -33,7 +33,9 @@ > #define VIRTIO_BALLOON_F_STATS_VQ 1 /* Memory Stats virtqueue */ > > /* Size of a PFN in the balloon interface. */ > -#define VIRTIO_BALLOON_PFN_SHIFT 12 > +#define VIRTIO_BALLOON_PFN_SHIFT 20 > +#define VIRTIO_BALLOON_PAGE_ORDER (VIRTIO_BALLOON_PFN_SHIFT - PAGE_SHIFT) > +#define VIRTIO_BALLOON_PAGES (1U<< VIRTIO_BALLOON_PAGE_ORDER) > > struct virtio_balloon_config > {