Commit a087628d authored by Olaf Hering's avatar Olaf Hering

xenpaging: implement stack of free slots in pagefile

Scanning the slot_to_gfn[] array for a free slot is expensive because
evict_pages() always needs to scan the whole array. Remember the last
slots freed during page-in requests and reuse them in evict_pages().
Signed-off-by: default avatarOlaf Hering <olaf@aepfle.de>
Committed-by: Ian Jackson <ian.jackson.citrix.com>
parent e148caed
......@@ -432,6 +432,11 @@ static struct xenpaging *xenpaging_init(int argc, char *argv[])
if ( !paging->slot_to_gfn || !paging->gfn_to_slot )
goto err;
/* Allocate stack for known free slots in pagefile */
paging->free_slot_stack = calloc(paging->max_pages, sizeof(*paging->free_slot_stack));
if ( !paging->free_slot_stack )
goto err;
/* Initialise policy */
rc = policy_init(paging);
if ( rc != 0 )
......@@ -483,6 +488,7 @@ static struct xenpaging *xenpaging_init(int argc, char *argv[])
free(dom_path);
free(watch_target_tot_pages);
free(paging->free_slot_stack);
free(paging->slot_to_gfn);
free(paging->gfn_to_slot);
free(paging->bitmap);
......@@ -807,6 +813,20 @@ static int evict_pages(struct xenpaging *paging, int num_pages)
xc_interface *xch = paging->xc_handle;
int rc, slot, num = 0;
/* Reuse known free slots */
while ( paging->stack_count > 0 && num < num_pages )
{
slot = paging->free_slot_stack[--paging->stack_count];
rc = evict_victim(paging, slot);
if ( rc )
{
num = rc < 0 ? -1 : num;
return num;
}
num++;
}
/* Scan all slots slots for remainders */
for ( slot = 0; slot < paging->max_pages && num < num_pages; slot++ )
{
/* Slot is allocated */
......@@ -930,6 +950,9 @@ int main(int argc, char *argv[])
/* Clear this pagefile slot */
paging->slot_to_gfn[slot] = 0;
/* Record this free slot */
paging->free_slot_stack[paging->stack_count++] = slot;
}
else
{
......
......@@ -60,6 +60,8 @@ struct xenpaging {
int policy_mru_size;
int use_poll_timeout;
int debug;
int stack_count;
int *free_slot_stack;
unsigned long pagein_queue[XENPAGING_PAGEIN_QUEUE_SIZE];
};
......
Markdown is supported
0% or
You are about to add 0 people to the discussion. Proceed with caution.
Finish editing this message first!
Please register or to comment