xenpaging: track the number of paged-out pages

This change is required by subsequent changes.

Signed-off-by: Olaf Hering <olaf@aepfle.de>
Committed-by: Ian Jackson <ian.jackson.citrix.com>

tools/xenpaging/xenpaging.c

@@ -467,6 +467,9 @@ static int xenpaging_evict_page(xenpaging_t *paging,
     /* Notify policy of page being paged out */
     policy_notify_paged_out(victim->gfn);
 
+    /* Record number of evicted pages */
+    paging->num_paged_out++;
+
  out:
     return ret;
 }
@@ -480,8 +483,13 @@ static int xenpaging_resume_page(xenpaging_t *paging, mem_event_response_t *rsp,
 
     /* Notify policy of page being paged in */
     if ( notify_policy )
+    {
         policy_notify_paged_in(rsp->gfn);
 
+       /* Record number of resumed pages */
+       paging->num_paged_out--;
+    }
+
     /* Tell Xen page is ready */
     ret = xc_mem_paging_resume(paging->xc_handle, paging->mem_event.domain_id,
                                rsp->gfn);

tools/xenpaging/xenpaging.h

@@ -49,6 +49,7 @@ typedef struct xenpaging {
     mem_event_t mem_event;
     /* number of pages for which data structures were allocated */
     int max_pages;
+    int num_paged_out;
     int num_pages;
     int policy_mru_size;
     unsigned long pagein_queue[XENPAGING_PAGEIN_QUEUE_SIZE];