On Dec 6, 2013, at 11:02 AM, Ben Pfaff <b...@nicira.com> wrote: > On Thu, Dec 05, 2013 at 04:27:26PM -0800, Jarno Rajahalme wrote: >> Add a prefix tree (trie) structure for tracking the used address >> space, enabling skipping classifier tables containing longer masks >> than necessary for an address field value in a packet header being >> classified. This enables less unwildcarding for datapath flows in >> parts of the address space without host routes. >> >> Trie lookup is interwoven to the staged lookup, so that a trie is >> searched only when the configured trie field becomes relevant >> for the lookup. The trie lookup results are retained so that each >> trie is checked at most once for each classifier lookup. >> >> This implementation tracks the number of rules at each address prefix >> for the whole classifier. More aggressive table skipping would be >> possible by maintaining lists of tables that have prefixes at the >> lengths encountered on tree traversal, or by maintaining separate >> tries for subsets of rules separated by metadata fields. >> >> Prefix tracking is configured via OVSDB. A new column "prefixes" is >> added to the database table "Flow_Table". "prefixes" is a set of >> string values listing the field names for which prefix lookup should >> be used. >> >> As of now, the fields for which prefix lookup can be enabled are: >> - tun_id, tun_src, tun_dst >> - nw_src, nw_dst (or aliases ip_src and ip_dst) >> - ipv6_src, ipv6_dst >> >> There is a maximum number of fields that can be enabled for any one >> flow table. Currently this limit is 3. >> >> Examples: >> >> ovs-vsctl set Bridge br0 flow_tables:0=@N1 -- \ >> --id=@N1 create Flow_Table name=table0 >> ovs-vsctl set Bridge br0 flow_tables:1=@N1 -- \ >> --id=@N1 create Flow_Table name=table1 >> >> ovs-vsctl set Flow_Table table0 prefixes=ip_dst,ip_src >> ovs-vsctl set Flow_Table table1 prefixes=[] >> >> Signed-off-by: Jarno Rajahalme <jrajaha...@nicira.com> > > Clang reports: > ../lib/classifier.c:1570:40: error: bad constant expression > referring to this line in trie_remove(): > struct trie_node *nodes[trie->field->n_bytes]; >
Mine is not doing that, running clang 1:3.4~svn193316-1~exp1. Anyway allocating variable sized arrays from stack is a C99 feature that CodingStyle does not seem to mention. I guess it would be better avoiding it then and replace the size with the biggest possible (sizeof(union mf_value) * 8) (and I was missing the “* 8” multiplier from it anyway, the size needs to be the max possible depth of the tree! > I'll have more comments later today. OK, thanks! Jarno
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