> On 21 Apr 2015, at 17:01, Loftus, Ciara <ciara.lof...@intel.com> wrote: > > > >> -----Original Message----- >> From: Ben Pfaff [mailto:b...@nicira.com] >> Sent: Tuesday, April 21, 2015 4:08 PM >> To: Loftus, Ciara >> Cc: dev@openvswitch.org >> Subject: Re: [ovs-dev] [PATCH RFC 0/1] dpif-netdev: Make EMC Size >> Configurable >> >> On Tue, Apr 21, 2015 at 01:47:12PM +0100, Ciara Loftus wrote: >>> This patch allows the user to specify the number of Exact Match Cache >>> entries they wish to have available for their instance of the vswitch. >>> This is a achieved by means of a 'configure' flag. >>> >>> At the moment, the default number of EMC entries is 1024, for which >>> the switch should perform optimally up to this number of flows. >>> However, if the user expects say roughly 2000 flows of traffic, an EMC >>> with 2048 entries will perform better, allbeit with a larger demand on >>> memory and time spent flushing the cache. If these requirements are >>> acceptable to the user, they may choose to allocate 2048 entries like so, >>> and in turn receive improved performance for their specific use case: >>> >>> './configure --with-emcsize=11' >>> >>> The number of entries is calculated as 2^11 = 2048. >> >> configure flags are really inconvenient. Is there a reason that this >> can't be made configurable at runtime? It would be better yet if the >> EMC size could automatically adjust itself. > > Thanks for the feedback. The implementation is naturally more complex for a > runtime configurable but I think achievable - I'll look into it.
Making it configurable at runtime is an option, but if that turns out to be too complex I think we could just make it bigger. Each entry takes 176 bytes. We could, for example, reserve 16K entries: that would take only 2.8 MB per core and (IMHO) it's totally reasonable to reserve that memory in userspace. What do you guys think? I'm CCing Ethan, as he might be interested in this too. _______________________________________________ dev mailing list dev@openvswitch.org http://openvswitch.org/mailman/listinfo/dev
