mainlining shenanigans
7dee607ed0
During connection tracking offloads with high number of connections,
(40K connections per second), flow table group lock contention is
observed.
To improve the performance by reducing lock contention, lockless
FTE read lookup is performed as described below.
Each flow table entry is refcounted.
Flow table entry is removed when refcount drops to zero.
rhash table allows rcu protected lookup.
Each hash table entry insertion and removal is write lock protected.
Hence, it is possible to perform lockless lookup in rhash table using
following scheme.
(a) Guard FTE entry lookup per group using rcu read lock.
(b) Before freeing the FTE entry, wait for all readers to finish
accessing the FTE.
Below example of one reader and write in parallel racing, shows
protection in effect with rcu lock.
lookup_fte_locked()
rcu_read_lock();
search_hash_table()
existing_flow_group_write_lock();
tree_put_node(fte)
drop_ref_cnt(fte)
del_sw_fte(fte)
del_hash_table_entry();
call_rcu();
existing_flow_group_write_unlock();
get_ref_cnt(fte) fails
rcu_read_unlock();
rcu grace period();
[..]
kmem_cache_free(fte);
Signed-off-by: Parav Pandit <parav@mellanox.com>
Reviewed-by: Mark Bloch <markb@mellanox.com>
Signed-off-by: Saeed Mahameed <saeedm@mellanox.com>
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| arch | ||
| block | ||
| certs | ||
| crypto | ||
| Documentation | ||
| drivers | ||
| fs | ||
| include | ||
| init | ||
| ipc | ||
| kernel | ||
| lib | ||
| LICENSES | ||
| mm | ||
| net | ||
| samples | ||
| scripts | ||
| security | ||
| sound | ||
| tools | ||
| usr | ||
| virt | ||
| .clang-format | ||
| .cocciconfig | ||
| .get_maintainer.ignore | ||
| .gitattributes | ||
| .gitignore | ||
| .mailmap | ||
| COPYING | ||
| CREDITS | ||
| Kbuild | ||
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| MAINTAINERS | ||
| Makefile | ||
| README | ||
Linux kernel
============
There are several guides for kernel developers and users. These guides can
be rendered in a number of formats, like HTML and PDF. Please read
Documentation/admin-guide/README.rst first.
In order to build the documentation, use ``make htmldocs`` or
``make pdfdocs``. The formatted documentation can also be read online at:
https://www.kernel.org/doc/html/latest/
There are various text files in the Documentation/ subdirectory,
several of them using the Restructured Text markup notation.
Please read the Documentation/process/changes.rst file, as it contains the
requirements for building and running the kernel, and information about
the problems which may result by upgrading your kernel.