On Thu, Sep 6, 2018 at 12:21 PM Olof Johansson <olof@xxxxxxxxx> wrote: > > Today these are all global shared variables per protocol, and in > particular tcp_memory_allocated can get hot on a system with > large number of CPUs and a substantial number of connections. > > Moving it over to a per-cpu variable makes it significantly cheaper, > and the added overhead when summing up the percpu copies is still smaller > than the cost of having a hot cacheline bouncing around. I am curious. We never noticed contention on this variable, at least for TCP. Please share some numbers with us.
