[lkarsten]

How do you think the CPU usage would be with 10kB buffer sizes? And since we're throwing numbers out in the air, why stop at 10kB? If we reduce to 1k, that should give us MUCH MOR connections!!11.

Let me ask a leading question: how much of this do you think is openssl overhead?

Please consider optimising for a real usage scenario, not some fantasy benchmarking setup.

[mrb]

I am not picking my numbers randomly. On a x86/x86-64 Linux kernel, one socket (one connection) will use at least one 4kB physical memory page. So if userland also allocates one or two 4kB pages for its own needs, you need at minimum 8 to 12kB per connection. That's why I quoted ~10kB.

The minimum theoretical memory usage is 4kB per connection: 1 page in kernel space, and nothing on the userland (eg. you use zero-copy to txfer data between sockets or to/from file descriptors).

At Google, our SSL/TLS overhead per connection is 10kB: https://www.imperialviolet.org/2010/06/25/overclocking-ssl.h...

[lkarsten]

Thanks for the data point.