[limoce]

  I am not 100% sure that all of the mitigation overhead 
  comes from syscalls, but it stands to reason that a lot 
  of it arises from security hardening in user-to-kernel 
  and kernel-to-user transitions.

Will io_uring be also affected by Spectre mitigations given it has eliminated most kernel/user switches?

And did anyone do a head-to-head comparison between io_uring and DPDK?

[anonymoushn]

You can use io_uring with 0 steady-state context switches if you're willing to use 100% CPU on 2 cores :)

[thekozmo]

Good point. This is more of a tcp stack comparison between the kernel and userspace. Seastar has a sharded (per core) stack, which is very beneficial when the number of threads is high

[anonymoushn]

You can set up one or many rings per core, but the idea I alluded to elsewhere in this comment section of spending 2 cores to do kernel busy polling and userspace busy polling for a single ring is less useful if your alternative makes good use of all cores.