On Thu, Jun 25, 2015 at 06:11:03PM +0100, David Vrabel wrote:
> alloc_xenballooned_pages() is used to get ballooned pages to back
> foreign mappings etc. Instead of having to balloon out real pages,
> use (if supported) hotplugged memory.
>
> This makes more memory available to the guest and reduces
> fragmentation in the p2m.
>
> If userspace is lacking a udev rule (or similar) to online hotplugged
> regions automatically, alloc_xenballooned_pages() will timeout and
> fall back to the old behaviour of ballooning out pages.
>
> Signed-off-by: David Vrabel <david.vrabel@xxxxxxxxxx>
In general Reviewed-by: Daniel Kiper <daniel.kiper@xxxxxxxxxx> but...
> ---
> drivers/xen/balloon.c | 32 ++++++++++++++++++++++++++------
> include/xen/balloon.h | 1 +
> 2 files changed, 27 insertions(+), 6 deletions(-)
>
> diff --git a/drivers/xen/balloon.c b/drivers/xen/balloon.c
> index 95c261c..a26c5f3 100644
> --- a/drivers/xen/balloon.c
> +++ b/drivers/xen/balloon.c
> @@ -97,6 +97,7 @@ static xen_pfn_t frame_list[PAGE_SIZE / sizeof(unsigned long)];
>
> /* List of ballooned pages, threaded through the mem_map array. */
> static LIST_HEAD(ballooned_pages);
> +static DECLARE_WAIT_QUEUE_HEAD(balloon_wq);
>
> /* Main work function, always executed in process context. */
> static void balloon_process(struct work_struct *work);
> @@ -125,6 +126,7 @@ static void __balloon_append(struct page *page)
> list_add(&page->lru, &ballooned_pages);
> balloon_stats.balloon_low++;
> }
> + wake_up(&balloon_wq);
> }
>
> static void balloon_append(struct page *page)
> @@ -247,7 +249,8 @@ static enum bp_state reserve_additional_memory(void)
> int nid, rc;
> unsigned long balloon_hotplug;
>
> - credit = balloon_stats.target_pages - balloon_stats.total_pages;
> + credit = balloon_stats.target_pages + balloon_stats.target_unpopulated
> + - balloon_stats.total_pages;
>
> /*
> * Already hotplugged enough pages? Wait for them to be
> @@ -328,7 +331,7 @@ static struct notifier_block xen_memory_nb = {
> static enum bp_state reserve_additional_memory(void)
> {
> balloon_stats.target_pages = balloon_stats.current_pages;
> - return BP_DONE;
> + return BP_ECANCELED;
> }
> #endif /* CONFIG_XEN_BALLOON_MEMORY_HOTPLUG */
>
> @@ -532,13 +535,31 @@ int alloc_xenballooned_pages(int nr_pages, struct page **pages)
> {
> int pgno = 0;
> struct page *page;
> +
> mutex_lock(&balloon_mutex);
> +
> + balloon_stats.target_unpopulated += nr_pages;
> +
> while (pgno < nr_pages) {
> page = balloon_retrieve(true);
> if (page) {
> pages[pgno++] = page;
> } else {
> enum bp_state st;
> +
> + st = reserve_additional_memory();
> + if (st != BP_ECANCELED) {
...think if you use BP_ECANCELED in patch #6...
Daniel
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