Read/write concurrency of pvector library is implemented by a temp vector
and RCU protection. Considering performance reason, insertion does not
follow this scheme.
In insertion function, a thread fence ensures size increment is done
after new entry is stored. But there is no barrier in the iteration
fuction(pvector_cursor_init). Entry point access may be reordered before
loading vector size, so the invalid entry point may be loaded when vector
iteration.
This patch fixes it by acquire-release pair. It can guarantee new size is
observed by reader after new entry stored by writer. And this is
implemented by one-way barrier instead of two-way memory fence.
Fixes: fe7cfa5c3f19 ("lib/pvector: Non-intrusive RCU priority vector.")
Reviewed-by: Gavin Hu <Gavin.Hu@arm.com>
Reviewed-by: Lijian Zhang <Lijian.Zhang@arm.com>
Signed-off-by: Yanqin Wei <Yanqin.Wei@arm.com>
Signed-off-by: Ilya Maximets <i.maximets@ovn.org>
This reverts commit 8bdfe1313894047d44349fa4cf4402970865950f.
I failed to see that lib/dpif-netdev.c actually needs the concurrency
provided by pvector prior to this change. More specifically, when a
subtable is removed, concurrent lookups may skip over another subtable
swapped in to the place of the removed subtable in the vector.
Since this was the only use of the non-concurrent pvector, it is
cleaner to revert the whole patch.
Reported-by: Jan Scheurich <jan.scheurich@ericsson.com>
Signed-off-by: Jarno Rajahalme <jarno@ovn.org>
Acked-by: Daniele Di Proietto <diproiettod@vmware.com>
PMD threads use pvectors but do not need the overhead of the
concurrent version. Expose the non-concurrent version for
that use.
Note that struct pvector is renamed as struct cpvector (for concurrent
priority vector), and the former struct pvector_impl is now struct
pvector.
Signed-off-by: Jarno Rajahalme <jarno@ovn.org>
Acked-by: Ben Pfaff <blp@ovn.org>
Allow clients to use the whole priority range. Note that this changes
the semantics of PVECTOR_FOR_EACH_PRIORITY so that the iteration still
continues for entries at the given priority.
Suggested-by: Ben Pfaff <blp@ovn.org>
Signed-off-by: Jarno Rajahalme <jarno@ovn.org>
Acked-by: Ben Pfaff <blp@ovn.org>
There is no need to expose PVECTOR_EXTRA_ALLOC in the API.
Suggested-by: Ben Pfaff <blp@ovn.org>
Signed-off-by: Jarno Rajahalme <jarno@ovn.org>
Acked-by: Ben Pfaff <blp@ovn.org>
This patch adds a new functions classifier_defer() and
classifier_publish(), which control when the classifier modifications
are made available to lookups. By default, all modifications are made
available to lookups immediately. Modifications made after a
classifier_defer() call MAY be 'deferred' for later 'publication'. A
call to classifier_publish() will both publish any deferred
modifications, and cause subsequent changes to to be published
immediately.
Currently any deferring is limited to the visibility of the subtable
vector changes. pvector now processes modifications mostly in a
working copy, which needs to be explicitly published with
pvector_publish(). pvector_publish() sorts the working copy and
removes gaps before publishing it.
This change helps avoiding O(n**2) memory behavior in corner cases,
where large number of rules with different masks are inserted or
deleted.
VMware-BZ: #1322017
Signed-off-by: Jarno Rajahalme <jrajahalme@nicira.com>
Acked-by: Ben Pfaff <blp@nicira.com>
OpenFlow has priorities in the 16-bit unsigned range, from 0 to 65535.
In the classifier, it is sometimes useful to be able to have values below
and above this range. With the 'unsigned int' type used for priorities
until now, there were no values below the range, so some code worked
around it by converting priorities to 64-bit signed integers. This didn't
seem so great to me given that a plain 'int' also had the needed range.
This commit therefore changes the type used for priorities to int.
The interesting parts of this change are in pvector.h and classifier.c,
where one can see the elimination of the use of int64_t.
Signed-off-by: Ben Pfaff <blp@nicira.com>
Acked-by: Jarno Rajahalme <jrajahalme@nicira.com>
Factor out the priority vector code from the classifier.
Making the classifier use RCU instead of locking requires parallel
access to the priority vector, pointing to subtables in descending
priority order. When a new subtable is added, a new copy of the
priority vector is allocated, while the current readers can keep on
using the old copy they started with. Adding and removing subtables
is usually less frequent than adding and removing rules, so this
should not have a visible performance implication. As an optimization
for the userspace datapath use, where all the subtables have the same
priority, new subtables can be added to the end of the vector without
reallocation and without disturbing readers.
cls_subtables_reset() is now removed, as it served its purpose in bug
hunting. Checks on the new pvector are now incorporated into
tests/test-classifier.c.
Signed-off-by: Jarno Rajahalme <jrajahalme@nicira.com>
Acked-by: Ben Pfaff <blp@nicira.com>
