On Thu, Mar 07, 2013 at 02:09:50PM +0100, Peter Krempa wrote:
> Qemu's implementation of virtio RNG supports rate limiting of the
> entropy used. This patch exposes the option to tune this functionality.
>
> This patch is based on qemu commit 904d6f588063fb5ad2b61998acdf1e73fb4
>
> The rate limiting is exported in the XML as:
> <devices>
> ...
> <rng model='virtio'>
> <rate period='1234'>4321</rate>
I find it wierd that we're mixing use of attributes with text
content here. I'd expect one style, or the other
eg
<rate period="1234" bytes="4321"/>
or
<rate>
<period>1234</period>
<bytes>5432</bytes>
</rate>
I prefer the style using attributes myself.
> diff --git a/src/conf/domain_conf.h b/src/conf/domain_conf.h
> index 2509193..e19b5c0 100644
> --- a/src/conf/domain_conf.h
> +++ b/src/conf/domain_conf.h
> @@ -1721,6 +1721,8 @@ enum virDomainRNGBackend {
> struct _virDomainRNGDef {
> int model;
> int backend;
> + unsigned int rate; /* bits per period */
Why are we using bits instead of bytes ? Do we really need to
be able to control this rate with a granularity of bits? It seems
overkill to me
> diff --git a/src/qemu/qemu_command.c b/src/qemu/qemu_command.c
> index 201fac1..c0f8dd2 100644
> --- a/src/qemu/qemu_command.c
> +++ b/src/qemu/qemu_command.c
> @@ -4255,6 +4255,15 @@ qemuBuildRNGDeviceArgs(virCommandPtr cmd,
>
> virBufferAsprintf(&buf, "virtio-rng-pci,rng=%s", dev->info.alias);
>
> + if (dev->rate > 0) {
> + /* qemu uses bytes */
> + virBufferAsprintf(&buf, ",max-bytes=%u", dev->rate / 8);
I expect we need to use VIR_DIV_UP here ? Though we can avoid
it if we just store bytes ourselves.
Daniel
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