netdev - Re: [PATCH bpf-next 03/29] bpf: introduce BPF token object

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Message-ID: <CAEf4BzYXm4ua+S+xgrKaXFak8c3-t35B8DASbsHb78GQZhkWzg@mail.gmail.com>
Date: Fri, 5 Jan 2024 14:06:55 -0800
From: Andrii Nakryiko <andrii.nakryiko@...il.com>
To: Linus Torvalds <torvalds@...uxfoundation.org>
Cc: Matthew Wilcox <willy@...radead.org>, Andrii Nakryiko <andrii@...nel.org>, bpf@...r.kernel.org, 
	netdev@...r.kernel.org, paul@...l-moore.com, brauner@...nel.org, 
	linux-fsdevel@...r.kernel.org, linux-security-module@...r.kernel.org, 
	kernel-team@...a.com
Subject: Re: [PATCH bpf-next 03/29] bpf: introduce BPF token object

On Fri, Jan 5, 2024 at 12:46 PM Linus Torvalds
<torvalds@...uxfoundation.org> wrote:
>
> On Fri, 5 Jan 2024 at 12:32, Matthew Wilcox <willy@...radead.org> wrote:
> >
> > I can't tell from the description whether there are going to be a lot of
> > these.  If there are, it might make sense to create a slab cache for
> > them rather than get them from the general-purpose kmalloc caches.
>
> I suspect it's a "count on the fingers of your hand" thing, and having
> a slab cache would be more overhead than you'd ever win.

Yes, you suspect right. It will be mostly one BPF token instance per
application, and even then only if the application is running within a
container that has BPF token set up (through BPF FS instance). So
yeah, slab cache seems like an overkill.

>
>            Linus