From mboxrd@z Thu Jan  1 00:00:00 1970
From: "Michael S. Tsirkin" <mst@redhat.com>
Subject: Re: [PATCH v2 repost 4/7] virtio-balloon: speed up inflate/deflate
 process
Date: Thu, 28 Jul 2016 00:39:14 +0300
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References: <1469582616-5729-1-git-send-email-liang.z.li@intel.com>
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Cc: Liang Li <liang.z.li@intel.com>, 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, dgilbert@redhat.com, quintela@redhat.com,
        Andrew Morton <akpm@linux-foundation.org>,
        Vlastimil Babka <vbabka@suse.cz>,
        Mel Gorman <mgorman@techsingularity.net>,
        Paolo Bonzini <pbonzini@redhat.com>,
        Cornelia Huck <cornelia.huck@de.ibm.com>,
        Amit Shah <amit.shah@redhat.com>
To: Dave Hansen <dave.hansen@intel.com>
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On Wed, Jul 27, 2016 at 09:03:21AM -0700, Dave Hansen wrote:
> On 07/26/2016 06:23 PM, Liang Li wrote:
> > +	vb->pfn_limit = VIRTIO_BALLOON_PFNS_LIMIT;
> > +	vb->pfn_limit = min(vb->pfn_limit, get_max_pfn());
> > +	vb->bmap_len = ALIGN(vb->pfn_limit, BITS_PER_LONG) /
> > +		 BITS_PER_BYTE + 2 * sizeof(unsigned long);
> > +	hdr_len = sizeof(struct balloon_bmap_hdr);
> > +	vb->bmap_hdr = kzalloc(hdr_len + vb->bmap_len, GFP_KERNEL);
> 
> This ends up doing a 1MB kmalloc() right?  That seems a _bit_ big.  How
> big was the pfn buffer before?


Yes I would limit this to 1G memory in a go, will result
in a 32KByte bitmap.

-- 
MST