[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]

Re: [Xen-devel] [PATCH net-next v7 4/9] xen-netback: Introduce TX grant mapping

On 13/03/14 10:17, Ian Campbell wrote:
Pulling out this one comment for the attention on the core Xen/Linux

On Thu, 2014-03-06 at 21:48 +0000, Zoltan Kiss wrote:
@@ -343,8 +347,26 @@ struct xenvif *xenvif_alloc(struct device *parent, domid_t 
        vif->pending_prod = MAX_PENDING_REQS;
        for (i = 0; i < MAX_PENDING_REQS; i++)
                vif->pending_ring[i] = i;
-       for (i = 0; i < MAX_PENDING_REQS; i++)
-               vif->mmap_pages[i] = NULL;
+       spin_lock_init(&vif->callback_lock);
+       spin_lock_init(&vif->response_lock);
+       /* If ballooning is disabled, this will consume real memory, so you
+        * better enable it. The long term solution would be to use just a
+        * bunch of valid page descriptors, without dependency on ballooning
+        */

I wonder if we ought to enforce this via Kconfig? i.e. making
CONFIG_XEN_BACKEND (or the individual backends) depend on BALLOON (or
select?) or by making CONFIG_XEN_BALLOON non-optional etc.
I support this idea, but let's have other's views.

IIRC David V was looking into a solution involving auto hotplugging a
new region to use for this case, but then I guess
CONFIG_XEN_BALLOON_MEMORY_HOTPLUG would equally need to be enabled.
Yes, if that happens in the near future, we shouldn't be bothered by the above right now.

+       err = alloc_xenballooned_pages(MAX_PENDING_REQS,
+                                      vif->mmap_pages,
+                                      false);

Xen-devel mailing list



Lists.xenproject.org is hosted with RackSpace, monitoring our
servers 24x7x365 and backed by RackSpace's Fanatical Support®.