net/fs: change busy poll time accounting

Suggested by Linus:
Changed time accounting for busy-poll:
- Make it microsecond based.
- Use unsigned longs.
- Revert back to use time_after instead of time_in_range.
Reorder poll/select busy loop conditions:
- Clear busy_flag after one time we can't busy-poll.
- Only init busy_end if we actually are going to busy-poll.
Added one more missing need_resched() test.

Signed-off-by: Eliezer Tamir <eliezer.tamir@linux.intel.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 20 insertions, 11 deletions

diff --git a/fs/select.c b/fs/select.c
index 25cac5faf6d6..50a804b6839f 100644
--- a/fs/select.c
+++ b/fs/select.c
@@ -403,8 +403,7 @@ int do_select(int n, fd_set_bits *fds, struct timespec *end_time)
         int retval, i, timed_out = 0;
         unsigned long slack = 0;
         unsigned int busy_flag = net_busy_loop_on() ? POLL_BUSY_LOOP : 0;
-        u64 busy_start = busy_loop_start_time(busy_flag);
-        u64 busy_end = busy_loop_end_time();
+        unsigned long busy_end = 0;
 
         rcu_read_lock();
         retval = max_select_fd(n, fds);
@@ -506,9 +505,15 @@ int do_select(int n, fd_set_bits *fds, struct timespec *end_time)
                 }
 
                 /* only if found POLL_BUSY_LOOP sockets && not out of time */
-                if (!need_resched() && can_busy_loop &&
-                    busy_loop_range(busy_start, busy_end))
-                        continue;
+                if (can_busy_loop && !need_resched()) {
+                        if (!busy_end) {
+                                busy_end = busy_loop_end_time();
+                                continue;
+                        }
+                        if (!busy_loop_timeout(busy_end))
+                                continue;
+                }
+                busy_flag = 0;
 
                 /*
                  * If this is the first loop and we have a timeout
@@ -780,9 +785,7 @@ static int do_poll(unsigned int nfds,  struct poll_list *list,
         int timed_out = 0, count = 0;
         unsigned long slack = 0;
         unsigned int busy_flag = net_busy_loop_on() ? POLL_BUSY_LOOP : 0;
-        u64 busy_start = busy_loop_start_time(busy_flag);
-        u64 busy_end = busy_loop_end_time();
-
+        unsigned long busy_end = 0;
 
         /* Optimise the no-wait case */
         if (end_time && !end_time->tv_sec && !end_time->tv_nsec) {
@@ -834,9 +837,15 @@ static int do_poll(unsigned int nfds,  struct poll_list *list,
                         break;
 
                 /* only if found POLL_BUSY_LOOP sockets && not out of time */
-                if (!need_resched() && can_busy_loop &&
-                    busy_loop_range(busy_start, busy_end))
-                        continue;
+                if (can_busy_loop && !need_resched()) {
+                        if (!busy_end) {
+                                busy_end = busy_loop_end_time();
+                                continue;
+                        }
+                        if (!busy_loop_timeout(busy_end))
+                                continue;
+                }
+                busy_flag = 0;
 
                 /*
                  * If this is the first loop and we have a timeout