Subject: Re: Upstream Homa?

From: Jiri Pirko <[email-masked]>
Date: Sat, 12 Nov 2022 08:53:43 +0100

Fri, Nov 11, 2022 at 08:25:44PM CET, [email-masked] wrote:
>On Fri, Nov 11, 2022 at 10:59:58AM -0800, John Ousterhout wrote:
>> The netlink and 32-bit kernel issues are new for me; I've done some digging to
>> learn more, but still have some questions.
>> 
>
>> * Is the intent that netlink replaces *all* uses of /proc and ioctl? Homa
>> currently uses ioctls on sockets for I/O (its APIs aren't sockets-compatible).

Why exactly it isn't sockets-comatible?

>> It looks like switching to netlink would double the number of system calls that
>> have to be invoked, which would be unfortunate given Homa's goal of getting the
>> lowest possible latency. It also looks like netlink might be awkward for
>> dumping large volumes of kernel data to user space (potential for buffer
>> overflow?).

Netlink is slow, you should use it for fast path. It is for
configuration and stats.