Re: [Xen-devel] [PATCH 1 of 2 V4] tools/libxc: Remus Checkpoint Compression

[George Dunlap <George.Dunlap@xxxxxxxxxxxxx>]

On Wed, Oct 19, 2011 at 7:50 PM,  <rshriram@xxxxxxxxx> wrote:
> +    /* Without checkpoint compression, the dirty pages, pfn arrays
> +     * and tailbuf (vcpu ctx, shared info page, etc.)  are written
> +     * directly to outbuf. All of this is done while the domain is
> +     * suspended.
> +     *
> +     * When checkpoint compression is enabled, the dirty pages are
> +     * buffered, compressed "after" the domain is resumed and then
> +     * written to outbuf. Since tailbuf data are collected while a
> +     * domain is suspended, they cannot be directly written to the
> +     * outbuf as there is no dirty page data preceeding tailbuf.
> +     *
> +     * So,two output buffers are maintained. Tailbuf data goes into
> +     * ob_tailbuf. The dirty pages are compressed after resuming the
> +     * domain and written to ob_pagebuf. ob_tailbuf is then appended
> +     * to ob_pagebuf and finally flushed out.
> +     */
> +    struct outbuf ob_pagebuf, ob_tailbuf, *ob = NULL;

Thanks, that's very helpful.

I don't have any more objections / comments.

 -George

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