[Xen-devel] [PATCH 6 of 9] xenpaging: add evict_pages function

[Olaf Hering <olaf@xxxxxxxxx>]

# HG changeset patch
# User Olaf Hering <olaf@xxxxxxxxx>
# Date 1316067230 -7200
# Node ID 3a3a5979b799d948802183d10d65894ee84a872f
# Parent  6beca8cbc2c92900859712f8738db17084bcebdb
xenpaging: add evict_pages function

Add new function to evict a couple of pages.
Allocate all possible slots in a paging file to allow growing and
shrinking of the number of paged-out pages. Adjust other places to
iterate over all slots.

This change is required by subsequent patches.

Signed-off-by: Olaf Hering <olaf@xxxxxxxxx>

diff -r 6beca8cbc2c9 -r 3a3a5979b799 tools/xenpaging/xenpaging.c
--- a/tools/xenpaging/xenpaging.c
+++ b/tools/xenpaging/xenpaging.c
@@ -597,6 +597,30 @@ static int evict_victim(xenpaging_t *pag
     return ret;
 }
 
+/* Evict a couple of pages and write them to a free slot in the paging file */
+static int evict_pages(xenpaging_t *paging, int fd, xenpaging_victim_t 
*victims, int num_pages)
+{
+    xc_interface *xch = paging->xc_handle;
+    int rc, slot, num = 0;
+
+    for ( slot = 0; slot < paging->max_pages && num < num_pages; slot++ )
+    {
+        /* Slot is allocated */
+        if ( victims[slot].gfn != INVALID_MFN )
+            continue;
+
+        rc = evict_victim(paging, &victims[slot], fd, slot);
+        if ( rc == -ENOSPC )
+            break;
+        if ( rc == -EINTR )
+            break;
+        if ( num && num % 100 == 0 )
+            DPRINTF("%d pages evicted\n", num);
+        num++;
+    }
+    return num;
+}
+
 int main(int argc, char *argv[])
 {
     struct sigaction act;
@@ -639,7 +663,12 @@ int main(int argc, char *argv[])
         return 2;
     }
 
-    victims = calloc(paging->num_pages, sizeof(xenpaging_victim_t));
+    /* Allocate upper limit of pages to allow growing and shrinking */
+    victims = calloc(paging->max_pages, sizeof(xenpaging_victim_t));
+
+    /* Mark all slots as unallocated */
+    for ( i = 0; i < paging->max_pages; i++ )
+        victims[i].gfn = INVALID_MFN;
 
     /* ensure that if we get a signal, we'll do cleanup, then exit */
     act.sa_handler = close_handler;
@@ -653,18 +682,7 @@ int main(int argc, char *argv[])
     /* listen for page-in events to stop pager */
     create_page_in_thread(paging);
 
-    /* Evict pages */
-    for ( i = 0; i < paging->num_pages; i++ )
-    {
-        rc = evict_victim(paging, &victims[i], fd, i);
-        if ( rc == -ENOSPC )
-            break;
-        if ( rc == -EINTR )
-            break;
-        if ( i % 100 == 0 )
-            DPRINTF("%d pages evicted\n", i);
-    }
-
+    i = evict_pages(paging, fd, victims, paging->num_pages);
     DPRINTF("%d pages evicted. Done.\n", i);
 
     /* Swap pages in and out */
@@ -690,13 +708,13 @@ int main(int argc, char *argv[])
             if ( test_and_clear_bit(req.gfn, paging->bitmap) )
             {
                 /* Find where in the paging file to read from */
-                for ( i = 0; i < paging->num_pages; i++ )
+                for ( i = 0; i < paging->max_pages; i++ )
                 {
                     if ( victims[i].gfn == req.gfn )
                         break;
                 }
     
-                if ( i >= paging->num_pages )
+                if ( i >= paging->max_pages )
                 {
                     DPRINTF("Couldn't find page %"PRIx64"\n", req.gfn);
                     goto out;

_______________________________________________
Xen-devel mailing list
Xen-devel@xxxxxxxxxxxxxxxxxxx
http://lists.xensource.com/xen-devel