Mailing List Archive

# HG changeset patch
# User Olaf Hering <olaf@aepfle.de>
# Date 1321804959 -3600
# Node ID 35a65cd961e7ba04350ce0fe539f677dd4722b93
# Parent 927af61e2c89bf70c3e873140750aa897fb575e9
xenpaging: move page add/resume loops into its own function.

Move page resume loop into its own function.
Move page eviction loop into its own function.
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.

v2:
- check if victims allocation succeeded

Signed-off-by: Olaf Hering <olaf@aepfle.de>

diff -r 927af61e2c89 -r 35a65cd961e7 tools/xenpaging/xenpaging.c
--- a/tools/xenpaging/xenpaging.c
+++ b/tools/xenpaging/xenpaging.c
@@ -553,6 +553,27 @@ static int xenpaging_populate_page(xenpa
return ret;
}

+/* Trigger a page-in for a batch of pages */
+static void resume_pages(xenpaging_t *paging, int num_pages)
+{
+ xc_interface *xch = paging->xc_handle;
+ int i, num = 0;
+
+ for ( i = 0; i < paging->max_pages && num < num_pages; i++ )
+ {
+ if ( test_bit(i, paging->bitmap) )
+ {
+ paging->pagein_queue[num] = i;
+ num++;
+ if ( num == XENPAGING_PAGEIN_QUEUE_SIZE )
+ break;
+ }
+ }
+ /* num may be less than num_pages, caller has to try again */
+ if ( num )
+ page_in_trigger();
+}
+
static int evict_victim(xenpaging_t *paging,
xenpaging_victim_t *victim, int fd, int i)
{
@@ -596,6 +617,30 @@ static int evict_victim(xenpaging_t *pag
return ret;
}

+/* Evict a batch 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;
@@ -638,7 +683,14 @@ 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));
+ if ( !victims )
+ goto out;
+
+ /* 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;
@@ -652,18 +704,7 @@ 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 */
@@ -689,13 +730,13 @@ 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;
@@ -767,25 +808,12 @@ int main(int argc, char *argv[])
/* Write all pages back into the guest */
if ( interrupted == SIGTERM || interrupted == SIGINT )
{
- int num = 0;
- for ( i = 0; i < paging->max_pages; i++ )
- {
- if ( test_bit(i, paging->bitmap) )
- {
- paging->pagein_queue[num] = i;
- num++;
- if ( num == XENPAGING_PAGEIN_QUEUE_SIZE )
- break;
- }
- }
- /*
- * One more round if there are still pages to process.
- * If no more pages to process, exit loop.
- */
- if ( num )
- page_in_trigger();
- else if ( i == paging->max_pages )
+ /* If no more pages to process, exit loop. */
+ if ( !paging->num_paged_out )
break;
+
+ /* One more round if there are still pages to process. */
+ resume_pages(paging, paging->num_paged_out);
}
else
{

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