We currently have a poll_fd_wait_event(fd, wevent, events) function that
is used at places common to Windows and Linux where we have to wait on
sockets. On Linux, 'wevent' is always set as zero. On Windows, for sockets,
when we send both 'fd' and 'wevent', we associate them with each other for
'events' and then wait on 'wevent'. Also on Windows, when we only send 'wevent'
to this function, we would simply wait for all events for that 'wevent'.
There is a disadvantage with this approach.
* Windows clients need to create a 'wevent' and then pass it along. This
means that at a lot of places where we create sockets, we also are forced
to create a 'wevent'.
With this commit, we pass the responsibility of creating a 'wevent' to
poll_fd_wait() in case of sockets. That way, a client using poll_fd_wait()
is only concerned about sockets and not about 'wevents'. There is a potential
disadvantage with this change in that we create events more often and that
may have a performance penalty. If that turns out to be the case, we will
eventually need to create a pool of wevents that can be re-used.
In Windows, there are cases where we want to wait on a event (not
associated with any sockets) and then control it using functions
like SetEvent() etc. For that purpose, introduce a new function
poll_wevent_wait(). For this function, the client needs to create a event
and then pass it along as an argument.
Signed-off-by: Gurucharan Shetty <gshetty@nicira.com>
Acked-By: Ben Pfaff <blp@nicira.com>
This is helpful if we want to wait either on 'fd' for POSIX or
events for Windows.
For Windows, if both 'fd' and 'wevent' is specified, we associate
that event with the 'fd' using WSAEventSelect() in poll_block().
So any 'events' on that 'fd' will wake us up from WaitForMultipleObjects().
WSAEventSelect() does not understand POLLIN, POLLOUT etc. Instead the
macros it understands are FD_READ, FD_ACCEPT, FD_CONNECT, FD_CLOSE etc.
So we need to make that transition.
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>
In C, one can do preprocessor tricks by making a macro expansion include
the macro's own name. We actually used this in the tree to automatically
provide function arguments, e.g.:
int f(int x, const char *file, int line);
#define f(x) f(x, __FILE__, __LINE__)
...
f(1); /* Expands to a call like f(1, __FILE__, __LINE__); */
However it's somewhat confusing, so this commit stops using that trick.
Reported-by: Ed Maste <emaste@freebsd.org>
Signed-off-by: Ben Pfaff <blp@nicira.com>
Acked-by: Ed Maste <emaste@freebsd.org>
The simplification comes from dropping support for canceling a
poll_waiter, which was a feature that was never used. The speedup
comes from avoiding a malloc() for every call to poll_fd_wait().
(I doubt that this significantly improves performance.)
This prepares for making the polling structures per-thread in
the next commit.
Signed-off-by: Ben Pfaff <blp@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>
This reverts commit 1e276d1a10539a8cd97d2ad63c073a9a43f0f1ef.
The poll_fd_woke() and nl_sock_woke() function added in that commit are
no longer used, so there is no reason to keep them in the tree.
Each time we run through the poll loop, we check all file descriptors
that we were waiting on to see if there is data available. However,
this requires a system call and poll already provides information on
which FDs caused the wakeup so it is inefficient as the number of
active FDs grows. This provides a way to check whether a given FD
has data.
Until now, when the poll_loop module's log level was turned up to "debug",
it would log a backtrace of the call stack for the event that caused poll()
to wake up in poll_block(). This was pretty useful from time to time to
find out why ovs-vswitchd was using more CPU than expected, because we
could find out what was causing it to wake up.
But there were some issues. One is simply that the backtrace was printed
as a series of hexadecimal numbers, so GDB or another debugger was needed
to translate it into human-readable format. Compiler optimizations meant
that even the human-readable backtrace wasn't, in my experience, as helpful
as it could have been. And, of course, one needed to have the binary to
interpret the backtrace. When the backtrace couldn't be interpreted or
wasn't meaningful, there was essentially nothing to fall back on.
This commit changes the way that "debug" logging for poll_block() wakeups
works. Instead of logging a backtrace, it logs the source code file name
and line number of the call to a poll_loop function, using __FILE__ and
__LINE__. This is by itself much more meaningful than a sequence of
hexadecimal numbers, since no additional interpretation is necessary. It
can be useful even if the Open vSwitch version is only approximately known.
In addition to the file and line, this commit adds, for wakeups caused by
file descriptors, information about the file descriptor itself: what kind
of file it is (regular file, directory, socket, etc.), the name of the file
(on Linux only), and the local and remote endpoints for socket file
descriptors.
Here are a few examples of the new output format:
932-ms timeout at ../ofproto/in-band.c:507
[POLLIN] on fd 20 (192.168.0.20:35388<->192.168.0.3:6633) at ../lib/stream-fd.c:149
[POLLIN] on fd 7 (FIFO pipe:[48049]) at ../lib/fatal-signal.c:168
Every so often I get concerned because OVS does most of its time arithmetic
in "long long int" but poll_timer_wait() takes an "int", so there is
potential for truncating a large value to a small value or a positive value
to a negative value. That would cause excessive wakeups and possibly 100%
CPU usage.
This commit therefore changes poll_timer_wait()'s parameter type from "int"
to "long long int". The file-scope 'timeout' variable remains type "int"
because that is the type of poll()'s timeout argument.
Factoring poll_timer_wait() into two functions is not necessary here but it
comes in handy in the following patch.
The last user of this feature has been removed, so delete the feature too,
simplifying poll-loop.c significantly.
poll_cancel() is no longer used, either, but deleting it is much less
beneficial.
