Olaf Hering
2012-Jan-09 13:59 UTC
[PATCH] xenpaging: no poll timeout while page-out is in progress
# HG changeset patch
# User Olaf Hering <olaf@aepfle.de>
# Date 1326117284 -3600
# Node ID 3394ca5ef6f768aa2fe0988c121b2a86698f1400
# Parent 3a22ed3ec534799b3cab55b0dc0a7380e701ecbe
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().
Signed-off-by: Olaf Hering <olaf@aepfle.de>
diff -r 3a22ed3ec534 -r 3394ca5ef6f7 tools/xenpaging/policy_default.c
--- a/tools/xenpaging/policy_default.c
+++ b/tools/xenpaging/policy_default.c
@@ -90,6 +90,7 @@ int policy_choose_victim(xenpaging_t *pa
/* 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) */
diff -r 3a22ed3ec534 -r 3394ca5ef6f7 tools/xenpaging/xenpaging.c
--- a/tools/xenpaging/xenpaging.c
+++ b/tools/xenpaging/xenpaging.c
@@ -85,6 +85,7 @@ static int xenpaging_wait_for_event_or_t
struct pollfd fd[2];
int port;
int rc;
+ int timeout;
/* Wait for event channel and xenstore */
fd[0].fd = xc_evtchn_fd(xce);
@@ -92,7 +93,9 @@ static int xenpaging_wait_for_event_or_t
fd[1].fd = xs_fileno(paging->xs_handle);
fd[1].events = POLLIN | POLLERR;
- rc = poll(fd, 2, 100);
+ /* No timeout while page-out is still in progress */
+ timeout = paging->use_poll_timeout ? 100 : 0;
+ rc = poll(fd, 2, timeout);
if ( rc < 0 )
{
if (errno == EINTR)
@@ -134,6 +137,8 @@ static int xenpaging_wait_for_event_or_t
if ( target_tot_pages < 0 || target_tot_pages >
paging->max_pages )
target_tot_pages = paging->max_pages;
paging->target_tot_pages = target_tot_pages;
+ /* Disable poll() delay while new target is not yet
reached */
+ paging->use_poll_timeout = 0;
DPRINTF("new target_tot_pages %d\n",
target_tot_pages);
}
free(val);
@@ -985,6 +990,11 @@ int main(int argc, char *argv[])
}
resume_pages(paging, num);
}
+ /* Now target was reached, enable poll() timeout */
+ else
+ {
+ paging->use_poll_timeout = 1;
+ }
}
DPRINTF("xenpaging got signal %d\n", interrupted);
diff -r 3a22ed3ec534 -r 3394ca5ef6f7 tools/xenpaging/xenpaging.h
--- a/tools/xenpaging/xenpaging.h
+++ b/tools/xenpaging/xenpaging.h
@@ -52,6 +52,7 @@ typedef struct xenpaging {
int num_paged_out;
int target_tot_pages;
int policy_mru_size;
+ int use_poll_timeout;
int debug;
unsigned long pagein_queue[XENPAGING_PAGEIN_QUEUE_SIZE];
} xenpaging_t;