The new command is of the form 'time/warp LARGE_MSECS MSECS'.
It advances the current monotonic time by LARGE_MSECS. This is done MSECS
at a time in each run of the main thread. This gives other threads
time to run after the clock has been advanced by MSECS.
The old command would continue to work.
Rationale: On Windows, process creation is slower. When we have tests
that run 'ovs-appctl time/warp MSECS' hundreds of times in a for loop,
the time it takes to complete the test increases. This is specially
true for bfd tests. For e.g, the 11 bfd tests would take 3.5 minutes
to complete before this change and now takes a little less than 2 minutes.
Signed-off-by: Gurucharan Shetty <gshetty@nicira.com>
Acked-by: Ben Pfaff <blp@nicira.com>
Use WaitForMultipleObjects for polling on windows. This works on all kinds
of objects, e.g. sockets, files, especially ioctl calls to the kernel.
poll_fd_wait_event() is used if events need to be passed to pollfds. latch
is signaled with event, to be waited/polled by WaitForMultipleObjects() as
well. Changed array of fds to hmap to check for duplicate fds.
Signed-off-by: Linda Sun <lsun@vmware.com>
Signed-off-by: Ben Pfaff <blp@nicira.com>
This commit makes the main thread wake up all other threads when time is
warped.
Signed-off-by: Alex Wang <alexw@nicira.com>
Signed-off-by: Ethan Jackson <ethan@nicira.com>
Acked-by: Ben Pfaff <blp@nicira.com>
Acked-by: Ethan Jackson <ethan@nicira.com>
This commit removes the CACHE_TIME scheme from timeval module. This
is for eliminating the lock contention over the read/write lock of
the cached time. To get the time, the thread now will directly do
the system call 'clock_gettime()'.
As a side effect, timer can only be warpped after timer is stopped
by 'appctl time/stop' command.
Signed-off-by: Alex Wang <alexw@nicira.com>
Signed-off-by: Ethan Jackson <ethan@nicira.com>
Acked-by: Ethan Jackson <ethan@nicira.com>
The backtrace feature of timeval is useful because it provides a "poor
man's profile" view of Open vSwitch. But it is not likely to be useful in
a multithreaded process, because signal delivery doesn't necessarily follow
the profile when there is more than one thread. (A signal in a
multithreaded process are delivered to an arbitrary thread.)
Another problem with the backtrace feature is that it is difficult for
format_backtraces() to synchronize properly with the signal handler in a
multithreaded process. In a single-threaded process, it can just block
the signal handler, but in a multithreaded process this does not prevent
signal delivery to threads other than the one running format_backtrace().
Signed-off-by: Ben Pfaff <blp@nicira.com>
Acked-by: Ed Maste <emaste@freebsd.org>
These functions will not have the same useful effect when Open vSwitch
becomes multithreaded, because time_disable_restart() will disable time
advancing for every thread, not just for the thread that calls it.
These functions are no longer used, so this commit removes them.
Signed-off-by: Ben Pfaff <blp@nicira.com>
With CFM and other tunnel monitoring protocols, having a fairly precise
time is good. My measurements don't show this change increasing CPU use.
(In fact it appears to repeatably reduce CPU use slightly, from about
22% to about 20% with 1000 CFM instances, although it's not obvious why.)
Bug #15171.
Signed-off-by: Ben Pfaff <blp@nicira.com>
Acked-by: Ethan Jackson <ethan@nicira.com>
With CFM enabled on 1000 tunnels, this reduced CPU use from about 30% to
about 22%.
Bug #15171.
Signed-off-by: Ben Pfaff <blp@nicira.com>
Acked-by: Ethan Jackson <ethan@nicira.com>
Often when debugging Open vSwitch, one will see in the logs that
CPU usage has been high for some period of time, but it's totally
unclear why. In an attempt to remedy the situation, this patch
logs backtraces taken at regular intervals as a poor man's
profiling alternative.
Signed-off-by: Ethan Jackson <ethan@nicira.com>
Often when developing, it would be convenient to force OVS to
either enable or disable cached timing so that a feature can be
tested under both strategies.
Signed-off-by: Ethan Jackson <ethan@nicira.com>
The ESX userspace looks quite a bit like linux, but has some key
differences which need to be specially handled in the build. To
distinguish between ESX and systems which use the linux datapath
module, this patch adds two new macros "ESX" and "LINUX_DATAPATH".
It uses these macros to disable building code on ESX which only
applies to a true Linux environment. In addition, it adds a new
route-table-stub implementation which is required for the build to
complete successfully on ESX.
Signed-off-by: Ethan Jackson <ethan@nicira.com>
The timer_create() system call is not supported in ESX and returns
an error when called. Aborting when this system call fails seems a
bit extreme. So instead, this patch simply falls back to disabling
the cached time optimization.
Signed-off-by: Ethan Jackson <ethan@nicira.com>
64-bit Linux appears to avoid syscalls for clock_gettime(), so we can get
higher resolution timing and avoid having a timer firing off SIGALRM
without introducing extra overhead.
Signed-off-by: Leo Alterman <lalterman@nicira.com>
Replaced all instances of Nicira Networks(, Inc) to Nicira, Inc.
Feature #10593
Signed-off-by: Raju Subramanian <rsubramanian@nicira.com>
Signed-off-by: Ben Pfaff <blp@nicira.com>
An upcoming commit has a new use for the time at which OVS started up, so
this moves this functionality to a common location.
Signed-off-by: Ben Pfaff <blp@nicira.com>
This is a necessary prerequisite for allowing time to be "fast forwarded"
in unit tests, to keep tests that depend on the passage of time from
running in real time. Without this change, a code sequence like this:
poll_timer_wait(1000);
...fast forward time 5 seconds...
poll_block();
would still sleep for a second, because the poll_loop module would still
have a relative timeout of 1000 ms.
Signed-off-by: Ben Pfaff <blp@nicira.com>
For a long time, the poll-loop module has had the ability to log the reason
for wakeups, which is valuable for debugging excessive use of CPU time.
But I have to ask users to turn up the log level for the module, which
wastes their time and mine. This commit improves the situation by
automatically logging the reason for a wakeup whenever a process's
estimated CPU usage rises above 50%. (ovs-vswitchd often uses less than
1% CPU; more than 5% CPU is uncommon.)
Since the timeval module now initializes itself on-demand, there is no
longer any need to initialize it explicitly, or to provide an interface to
do so.
Most of the timekeeping needs of OVS are simply to measure intervals,
which means that it is sensitive to changes in the clock. This commit
replaces the existing clocks with monotonic timers. An additional set
of wall clock timers are added and used in locations that need absolute
time.
Bug #1858
Without removing SA_RESTART from the SIGALRM handler, the fcntl call will
never return, even after the signal handler is invoked and returns.
We haven't seen a problem in practice, at least not recently, but that's
probably just luck combined with not holding the configuration file lock
for very long.
Open vSwitch uses an interval timer signal to tell it that its cached idea
of the current time has expired. However, this didn't work in a daemon
detached from the foreground session (invoked with --detach) because a
child created with fork() does not inherit the parent's interval timer and
we did not re-set it after calling fork().
This commit fixes the problem by setting the interval timer back up after
calling fork() from daemonize().
This fix is based on code inspection (which was then verified to be correct
through testing). It may not fix any actual problems in practice, because
time_refresh() is called every time through the poll loop, and the poll
loop typically runs more quickly than the periodic timer fires (1 ms or so
average in ovs-vswitchd, vs. 100 ms timer interval).
