On Tue, Mar 04, 2014 at 06:44:01AM -0700, Eric Blake wrote:
On 03/03/2014 10:21 AM, Martin Kletzander wrote:
> When domain is started with setting that cannot be done, i.e. those
> that require cgroups, there is no error reported and it succeeds
> without any message whatsoever.
>
> When setting with API, virsh, an error is reported, but only due to
> the fact that no cgroups are mounted (priv->cgroup == NULL).
>
> Given the above it seems reasonable to reject such unsupported
> settings.
>
> Signed-off-by: Martin Kletzander <mkletzan(a)redhat.com>
> ---
>
> Notes:
> Few questions came to my mind while writing the commit message:
>
> 1) Would helper function (macro) be preferred so the code looks
> cleaner?
What macro do you have in mind?
I haven't thought that through, just from top of my head:
#define SESSION_UNSUPP(what) if (!cfg->privileged) { \
virReportError(VIR_ERR_CONFIG_UNSUPPORTED, "%s %s", \
what, _("is not available in sesison mode")); \
goto cleanup; \
}
because the code repeats a lot, but it seems like it would not be that
readable. Separate function would do as well.
>
> 2) Do we want to allow reading of some of these settings through an
> API? This would however require our cgroup handling to be
> reworked.
>
> 3) Would new error type (for session-unsupported settings) be any
> good or it doesn't make sense to create one just for these added
> messages plus few older ones (just guessing the amount)?
Looks like your use of VIR_ERR_CONFIG_UNSUPPORTED was reasonable.
> + if (!cfg->privileged) {
> + /* If we have no cgroups than we can have no tunings that
> + * require them */
> +
> + if (def->mem.hard_limit || def->mem.soft_limit ||
> + def->mem.min_guarantee || def->mem.swap_hard_limit) {
> + virReportError(VIR_ERR_CONFIG_UNSUPPORTED, "%s",
> + _("Memory tuning is not available in session
mode"));
> + goto error;
> + }
> +
Or maybe we should think about some day adding a daemon that accepts RPC
commands for manipulating cgroups on behalf of a session client. But
that would be a later and bigger patch.
I was just trying to output a better error message and forgot to add
the BZ that started it:
https://bugzilla.redhat.com/show_bug.cgi?id=1023366
Seems reasonable to me, but it might be nice to also get Dan's
opinion
on this one.
Anyway, I'll have a second version which allows at least cpu pinning
as setaffinity works and is used when no cgroups are available.
Martin