CPU - higher single Core Speed vs Multi Core



  • Hi, Does pfsense favour higher single Core Speeds but less cores or slower single Core Speeds but more cores.
    Now this depends on your setup or requirements but let’s say the scenario is

    Users 10 (30 devices)
    Connection speed 100mbps
    Packages
    Openvpn
    Squid (with caching and proxy http,https)
    Snort

    Now let's compare two cpus (7700K vs 1800X)

    http://cpu.userbenchmark.com/Compare/Intel-Core-i7-7700K-vs-AMD-Ryzen-7-1800X/3647vs3916

    The 7700K has a much faster single core clock speed but the 1800X has a much faster total core speed.

    So which would be best for pfsense, more cores or faster single core speed?



  • Without benchmarks for your specific use case, it's hard to say which is best, but my guess would be the quad core 4.2ghz. pfSense does make decent use of multi-core in many cases, but diminishing returns after 2-4 cores short of CPU bound work loads like many VPN tunnels.



  • Packet filtering itself  is hard to make take advantage of parallel execution because of stateful filtering and because the traffic has to be processed in order. Other services such as DNS resolvers etc. running on the router/firewall benefit more from multiple cores.



  • Whatever u do, just don't do it like that guy LinusTech in youtube, overkilled it with dual-xeon octo-core something but end up burning through 3 motherboards before giving up.


  • Netgate Administrator

    At 100Mbps both of those would be mostly idling! I doubt you could tell the difference between them.

    Steve



  • @SammyWoo:

    Whatever u do, just don't do it like that guy LinusTech in youtube, overkilled it with dual-xeon octo-core something but end up burning through 3 motherboards before giving up.

    But going with my original question, higher single core speed vs more cores it looks like even though the dual-xeon octo-core has more total compute power pfsense would better utilize a cpu with higher single core speed.

    another example

    CPU 1

    2 cores @ 2GHZ

    CPU 2

    8 cores @ 1GHZ

    Looks like the higher single core CPU will outperform the one with more cores and total compute power.


  • Netgate Administrator

    There are still some processes in pfSense that are thread-locked or do not scale well across cores and those benefit from faster CPU speed.

    If you run a number if things though, VPN, snort, squid etc, those can use separate cores so you would some benefit there.

    The sweet spot there depends what you're running but 4 fast cores is pretty good for a default setup.

    Steve