Date: Tue, 21 Apr 2015 09:14:24 +0300 From: Gleb Smirnoff <glebius@FreeBSD.org> To: Mark Johnston <markj@FreeBSD.org> Cc: melifaro@FreeBSD.org, freebsd-net@FreeBSD.org Subject: Re: moving struct bpf_if to bpf.c Message-ID: <20150421061424.GC883@glebius.int.ru> In-Reply-To: <20150420195233.GA71166@muskytusk> References: <20150418210855.GA50409@charmander.west.isilon.com> <20150420192618.GY883@FreeBSD.org> <20150420195233.GA71166@muskytusk>
next in thread | previous in thread | raw e-mail | index | archive | help
On Mon, Apr 20, 2015 at 07:52:33PM +0000, Mark Johnston wrote: M> On Mon, Apr 20, 2015 at 10:26:18PM +0300, Gleb Smirnoff wrote: M> > On Sat, Apr 18, 2015 at 02:08:56PM -0700, Mark Johnston wrote: M> > M> At the moment, bpf.h defines struct bpf_if differently depending on M> > M> whether BPF_INTERNAL is #defined. This causes problems with CTF, as it M> > M> results in a sort of bifurcation within the type graph: CTF sees two M> > M> different struct bpf_ifs, and so every struct/union containing a struct M> > M> bpf_if is duplicated, and so on. CTF currently imposes a limit of 2^15 M> > M> distinct types within a container, and several people have been running M> > M> into this limit. The type duplication exacerbates this problem. M> > M> M> > M> The change here fixes the issue by moving the definition of M> > M> struct bpf_if to bpf.c, and making its externally-used fields M> > M> available via struct bpf_if_ext: https://reviews.freebsd.org/D2319 M> > M> M> > M> In particular, the ext fields are at the same offsets within struct M> > M> bpf_if as before, so this change should have no functional impact. M> > M> Moreover, it reduces the number of types from 20879 to 15725 with my M> > M> (stripped-down) kernel config on amd64. Would anyone be willing to M> > M> review the proposed change? I've also placed the raw diff here: M> > M> https://people.freebsd.org/~markj/patches/bpf_entrails.diff M> > M> > What actual software needs to look at struct bpf_if? I wonder if M> > we can fix the software and hide the struct bpf_if into kernel M> > entirely. M> M> bpf_peers_present() is defined in bpf.h so that it can be inlined, and M> it needs access to the bif_dlist field of struct bpf_if. As far as I can M> see, this is the only reason for exposing part of struct bpf_if. My suggestion is to un-inline it. Calling a static function isn't a big deal on modern machines. -- Totus tuus, Glebius.
Want to link to this message? Use this URL: <https://mail-archive.FreeBSD.org/cgi/mid.cgi?20150421061424.GC883>