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Ido Schimmel says: ==================== vxlan: Convert FDB table to rhashtable The VXLAN driver currently stores FDB entries in a hash table with a fixed number of buckets (256), resulting in reduced performance as the number of entries grows. This patchset solves the issue by converting the driver to use rhashtable which maintains a more or less constant performance regardless of the number of entries. Measured transmitted packets per second using a single pktgen thread with varying number of entries when the transmitted packet always hits the default entry (worst case): Number of entries | Improvement ------------------|------------ 1k | +1.12% 4k | +9.22% 16k | +55% 64k | +585% 256k | +2460% The first patches are preparations for the conversion in the last patch. Specifically, the series is structured as follows: Patch #1 adds RCU read-side critical sections in the Tx path when accessing FDB entries. Targeting at net-next as I am not aware of any issues due to this omission despite the code being structured that way for a long time. Without it, traces will be generated when converting FDB lookup to rhashtable_lookup(). Patch #2-#5 simplify the creation of the default FDB entry (all-zeroes). Current code assumes that insertion into the hash table cannot fail, which will no longer be true with rhashtable. Patches #6-#10 add FDB entries to a linked list for entry traversal instead of traversing over them using the fixed size hash table which is removed in the last patch. Patches #11-#12 add wrappers for FDB lookup that make it clear when each should be used along with lockdep annotations. Needed as a preparation for rhashtable_lookup() that must be called from an RCU read-side critical section. Patch #13 treats dst cache initialization errors as non-fatal. See more info in the commit message. The current code happens to work because insertion into the fixed size hash table is slow enough for the per-CPU allocator to be able to create new chunks of per-CPU memory. Patch #14 adds an FDB key structure that includes the MAC address and source VNI. To be used as rhashtable key. Patch #15 does the conversion to rhashtable. ==================== Link: https://patch.msgid.link/20250415121143.345227-1-idosch@nvidia.com Signed-off-by: Paolo Abeni <pabeni@redhat.com>
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