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    SubjectRe: [PATCH RFC kernel] balloon: speed up inflating/deflating process
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    On 20/05/2016 11:59, Liang Li wrote:
    > +
    > + sg_init_table(sg, 5);
    > + sg_set_buf(&sg[0], &flags, sizeof(flags));
    > + sg_set_buf(&sg[1], &start_pfn, sizeof(start_pfn));
    > + sg_set_buf(&sg[2], &page_shift, sizeof(page_shift));
    > + sg_set_buf(&sg[3], &bmap_len, sizeof(bmap_len));

    These four should probably be placed in a single struct and therefore a
    single sg entry. It might even be faster to place it together with the
    bitmap, thus avoiding the use of indirect descriptors.

    You should also test ballooning of a 64GB guest after filling in the
    page cache, not just ballooning of a freshly booted 4GB guest. This
    will give you a much more sparse bitmap. Still, the improvement in
    sending PFNs to the host are impressive.

    Thanks,

    Paolo

    > + sg_set_buf(&sg[4], vb->page_bitmap +
    > + (start_pfn / BITS_PER_LONG), bmap_len);
    > + virtqueue_add_outbuf(vq, sg, 5, vb, GFP_KERNEL);

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