Make the read of the current seq->value atomic, i.e., not needing to
acquire the global mutex when reading it. On 64-bit systems, this
incurs no overhead, and it will avoid the mutex and potentially
a system call.
For incrementing the value followed by waking up the threads, we are
still taking the mutex, so the current behavior is not changing. The
seq_read() behavior is already defined as, "Returns seq's current
sequence number (which could change immediately)". So the change
should not impact the current behavior.
Signed-off-by: Eelco Chaudron <echaudro@redhat.com>
Reviewed-by: Simon Horman <simon.horman@corigine.com>
Signed-off-by: Ilya Maximets <i.maximets@ovn.org>
Using SHORT version of the *_SAFE loops makes the code cleaner and less
error prone. So, use the SHORT version and remove the extra variable
when possible for hmap and all its derived types.
In order to be able to use both long and short versions without changing
the name of the macro for all the clients, overload the existing name
and select the appropriate version depending on the number of arguments.
Acked-by: Dumitru Ceara <dceara@redhat.com>
Acked-by: Eelco Chaudron <echaudro@redhat.com>
Signed-off-by: Adrian Moreno <amorenoz@redhat.com>
Signed-off-by: Ilya Maximets <i.maximets@ovn.org>
Using the SHORT version of the *_SAFE loops makes the code cleaner
and less error-prone. So, use the SHORT version and remove the extra
variable when possible.
In order to be able to use both long and short versions without changing
the name of the macro for all the clients, overload the existing name
and select the appropriate version depending on the number of arguments.
Acked-by: Dumitru Ceara <dceara@redhat.com>
Acked-by: Eelco Chaudron <echaudro@redhat.com>
Signed-off-by: Adrian Moreno <amorenoz@redhat.com>
Signed-off-by: Ilya Maximets <i.maximets@ovn.org>
valgrind regards a block to be "possibly" leaked when no pointers exist to
the beginning of the block but some pointers do point to the middle of the
block. By moving the hmap_node in struct seq_waiter from the middle of the
struct to the beginning, as this commit does, the pointers to the node from
the hmap in struct seq point to the beginning of the block, which reassures
valgrind.
Signed-off-by: Ben Pfaff <blp@ovn.org>
Reviewed-by: Yifeng Sun <pkusunyifeng@gmail.com>
Poll-loop is the core to implement main loop. It should be available in
libopenvswitch.
Signed-off-by: Xiao Liang <shaw.leon@gmail.com>
Signed-off-by: Ben Pfaff <blp@ovn.org>
To easily allow both in- and out-of-tree building of the Python
wrapper for the OVS JSON parser (e.g. w/ pip), move json.h to
include/openvswitch. This also requires moving lib/{hmap,shash}.h.
Both hmap.h and shash.h were #include-ing "util.h" even though the
headers themselves did not use anything from there, but rather from
include/openvswitch/util.h. Fixing that required including util.h
in several C files mostly due to OVS_NOT_REACHED and things like
xmalloc.
Signed-off-by: Terry Wilson <twilson@redhat.com>
Signed-off-by: Ben Pfaff <blp@ovn.org>
The PMD thread needs to keep processing RX queues in order
to achieve maximum throughput. It also needs to sweep emc
cache and quiesce which use seq_mutex. That mutex can
eventually block the PMD thread causing latency spikes and
affecting the throughput.
Since there is no requirement for running those tasks at a
specific time, this patch extend seq API to allow tentative
locking instead.
Reported-by: Karl Rister <krister@redhat.com>
Co-authored-by: Karl Rister <krister@redhat.com>
Signed-off-by: Flavio Leitner <fbl@redhat.com>
Signed-off-by: Daniele Di Proietto <diproiettod@vmware.com>
This attempts to prevent namespace collisions with other list libraries
Signed-off-by: Ben Warren <ben@skyportsystems.com>
Signed-off-by: Ben Pfaff <blp@ovn.org>
Having a coverage counter tracking the value of the internal seq_next
should help in debugging.
Suggested-by: Justin Pettit <jpettit@ovn.org>
Signed-off-by: Jarno Rajahalme <jarno@ovn.org>
Acked-by: Ben Pfaff <blp@ovn.org>
struct list is a common name and can't be used in public headers.
Signed-off-by: Thomas Graf <tgraf@noironetworks.com>
Acked-by: Ben Pfaff <blp@nicira.com>
The poll_loop code has a feature that, when turned on manually or
automatically (due to high CPU use), logs the source file and line number
of the code that caused a thread to wake up from poll(). Until now, when
a function calls seq_wait(), the source file and line number logged was
the code inside seq_wait(). seq_wait() has many callers, so that
information is not as useful as it could be. This commit changes the
source file and line number used to be that of seq_wait()'s caller.
I found this useful for debugging.
Signed-off-by: Ben Pfaff <blp@nicira.com>
We've seen a number of deadlocks in the tree since thread safety was
introduced. So far, all of these are self-deadlocks, that is, a single
thread acquiring a lock and then attempting to re-acquire the same lock
recursively. When this has happened, the process simply hung, and it was
somewhat difficult to find the cause.
POSIX "error-checking" mutexes check for this specific problem (and
others). This commit switches from other types of mutexes to
error-checking mutexes everywhere that we can, that is, everywhere that
we're not using recursive mutexes. This ought to help find problems more
quickly in the future.
There might be performance advantages to other kinds of mutexes in some
cases. However, the existing mutex type choices were just guesses, so I'd
rather go for easy detection of errors until we know that other mutex
types actually perform better in specific cases. Also, I did a quick
microbenchmark of glibc mutex types on my host and found that the
error checking mutexes weren't any slower than the other types, at least
when the mutex is uncontended.
Signed-off-by: Ben Pfaff <blp@nicira.com>
Acked-by: Ethan Jackson <ethan@nicira.com>
