From: fche-H+wXaHxf7aLQT0dZR+AlfA@public•gmane.org (Frank Ch. Eigler)
To: Alexei Starovoitov <ast-uqk4Ao+rVK5Wk0Htik3J/w@public•gmane.org>
Cc: "David S. Miller" <davem-fT/PcQaiUtIeIZ0/mPfg9Q@public•gmane.org>,
Ingo Molnar <mingo-DgEjT+Ai2ygdnm+yROfE0A@public•gmane.org>,
Linus Torvalds
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Andy Lutomirski <luto-kltTT9wpgjJwATOyAt5JVQ@public•gmane.org>,
Steven Rostedt <rostedt-nx8X9YLhiw1AfugRpC6u6w@public•gmane.org>,
Daniel Borkmann
<dborkman-H+wXaHxf7aLQT0dZR+AlfA@public•gmane.org>,
Chema Gonzalez <chema-hpIqsD4AKlfQT0dZR+AlfA@public•gmane.org>,
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Andrew Morton
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Kees Cook <keescook-F7+t8E8rja9g9hUCZPvPmw@public•gmane.org>,
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linux-kernel-u79uwXL29TY76Z2rM5mHXA@public•gmane.org
Subject: Re: [PATCH RFC v3 net-next 3/3] samples: bpf: eBPF dropmon example in C
Date: Wed, 30 Jul 2014 11:45:28 -0400 [thread overview]
Message-ID: <y0m1tt226lj.fsf@fche.csb> (raw)
In-Reply-To: <1406000723-4872-4-git-send-email-ast-uqk4Ao+rVK5Wk0Htik3J/w@public.gmane.org> (Alexei Starovoitov's message of "Mon, 21 Jul 2014 20:45:23 -0700")
ast wrote earlier:
> [...]
> dtrace/systemtap/ktap approach is to use one script file that should provide
> all desired functionality. That architectural decision overcomplicated their
> implementations.
>
> eBPF follows split model: everything that needs to process millions of events
> per second needs to run in kernel and needs to be short and deterministic,
> all other things like aggregation and nice graphs should run in user space.
> [...]
For the record, this is not entirely accurate as to dtrace. dtrace
delegates aggregation and most reporting to userspace. Also,
systemtap is "short and deterministic" even for aggregations & nice
graphs, but since it limits its storage & cpu consumption, its
arrays/reports cannot get super large.
> [...]
> +SEC("events/skb/kfree_skb")
> +int bpf_prog2(struct bpf_context *ctx)
> +{
> +[...]
> + value = bpf_map_lookup_elem(&my_map, &loc);
> + if (value)
> + (*(long *) value) += 1;
> + else
> + bpf_map_update_elem(&my_map, &loc, &init_val);
> + return 0;
> +}
What kind of locking/serialization is provided by the ebpf runtime
over shared variables such as my_map?
- FChE
next prev parent reply other threads:[~2014-07-30 15:45 UTC|newest]
Thread overview: 8+ messages / expand[flat|nested] mbox.gz Atom feed top
2014-07-22 3:45 [PATCH RFC v3 net-next 0/3] eBPF examples in C Alexei Starovoitov
2014-07-22 3:45 ` [PATCH RFC v3 net-next 1/3] samples: bpf: elf file loader Alexei Starovoitov
2014-07-22 3:45 ` [PATCH RFC v3 net-next 2/3] samples: bpf: eBPF example in C Alexei Starovoitov
2014-07-22 3:45 ` [PATCH RFC v3 net-next 3/3] samples: bpf: eBPF dropmon " Alexei Starovoitov
[not found] ` <1406000723-4872-4-git-send-email-ast-uqk4Ao+rVK5Wk0Htik3J/w@public.gmane.org>
2014-07-30 15:45 ` Frank Ch. Eigler [this message]
2014-07-30 17:17 ` Alexei Starovoitov
2014-07-30 17:36 ` Frank Ch. Eigler
[not found] ` <20140730173638.GB8745-H+wXaHxf7aLQT0dZR+AlfA@public.gmane.org>
2014-07-30 18:53 ` Alexei Starovoitov
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