xenpaging: no poll timeout while page-out is in progress

The main loop calls xenpaging_wait_for_event_or_timeout() unconditionally
before doing any work. This function calls poll() with a timeout of 100ms. As
a result the page-out process is very slow due to the delay in poll().

Call poll() without timeout so that it returns immediately until the page-out
is done. Page-out is done when either the policy finds no more pages to
nominate or when the requested number of pages is reached.

The condition is cleared when a watch event arrives, so that processing the
new target is not delayed once again by poll().

v2:
- no poll timeout also when large number of evicts is pending

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

1 files changed, 1 insertions, 0 deletions

diff --git a/tools/xenpaging/policy_default.c b/tools/xenpaging/policy_default.c
index 596afc7d9a..7563720092 100644
--- a/tools/xenpaging/policy_default.c
+++ b/tools/xenpaging/policy_default.c
@@ -90,6 +90,7 @@ unsigned long policy_choose_victim(struct xenpaging *paging)
         /* Could not nominate any gfn */
         if ( wrap == current_gfn )
         {
+            paging->use_poll_timeout = 1;
             /* Count wrap arounds */
             unconsumed_cleared++;
             /* Force retry every few seconds (depends on poll() timeout) */