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net: Track start of busy loop instead of when it should end

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This patch flips the logic we were using to determine if the busy polling
has timed out.  The main motivation for this is that we will need to
support two different possible timeout values in the future and by
recording the start time rather than when we would want to end we can focus
on making the end_time specific to the task be it epoll or socket based
polling.

Signed-off-by: Alexander Duyck <alexander.h.duyck@intel.com>
Acked-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
This commit is contained in:
Alexander Duyck
2017-03-24 10:08:18 -07:00
committed by David S. Miller
parent 2b5cd0dfa3
commit 37056719bb
3 changed files with 52 additions and 44 deletions
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16
fs/select.c
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@@ -409,7 +409,7 @@ int do_select(int n, fd_set_bits *fds, struct timespec64 *end_time)
int retval, i, timed_out = 0;
u64 slack = 0;
unsigned int busy_flag = net_busy_loop_on() ? POLL_BUSY_LOOP : 0;
unsigned long busy_end = 0;
unsigned long busy_start = 0;
rcu_read_lock();
retval = max_select_fd(n, fds);
@@ -512,11 +512,11 @@ int do_select(int n, fd_set_bits *fds, struct timespec64 *end_time)
/* only if found POLL_BUSY_LOOP sockets && not out of time */
if (can_busy_loop && !need_resched()) {
if (!busy_end) {
busy_end = busy_loop_end_time();
if (!busy_start) {
busy_start = busy_loop_current_time();
continue;
}
if (!busy_loop_timeout(busy_end))
if (!busy_loop_timeout(busy_start))
continue;
}
busy_flag = 0;
@@ -800,7 +800,7 @@ static int do_poll(struct poll_list *list, struct poll_wqueues *wait,
int timed_out = 0, count = 0;
u64 slack = 0;
unsigned int busy_flag = net_busy_loop_on() ? POLL_BUSY_LOOP : 0;
unsigned long busy_end = 0;
unsigned long busy_start = 0;
/* Optimise the no-wait case */
if (end_time && !end_time->tv_sec && !end_time->tv_nsec) {
@@ -853,11 +853,11 @@ static int do_poll(struct poll_list *list, struct poll_wqueues *wait,
/* only if found POLL_BUSY_LOOP sockets && not out of time */
if (can_busy_loop && !need_resched()) {
if (!busy_end) {
busy_end = busy_loop_end_time();
if (!busy_start) {
busy_start = busy_loop_current_time();
continue;
}
if (!busy_loop_timeout(busy_end))
if (!busy_loop_timeout(busy_start))
continue;
}
busy_flag = 0;