netdev - Re: [PATCH v2 net-next] bpf: reduce verifier memory consumption

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Message-Id: <20171101.114138.794863370939731562.davem@davemloft.net>
Date:   Wed, 01 Nov 2017 11:41:38 +0900 (KST)
From:   David Miller <davem@...emloft.net>
To:     ast@...com
Cc:     daniel@...earbox.net, ecree@...arflare.com,
        jakub.kicinski@...ronome.com, netdev@...r.kernel.org,
        kernel-team@...com
Subject: Re: [PATCH v2 net-next] bpf: reduce verifier memory consumption

From: Alexei Starovoitov <ast@...com>
Date: Tue, 31 Oct 2017 18:16:05 -0700

> the verifier got progressively smarter over time and size of its internal
> state grew as well. Time to reduce the memory consumption.
> 
> Before:
> sizeof(struct bpf_verifier_state) = 6520
> After:
> sizeof(struct bpf_verifier_state) = 896
> 
> It's done by observing that majority of BPF programs use little to
> no stack whereas verifier kept all of 512 stack slots ready always.
> Instead dynamically reallocate struct verifier state when stack
> access is detected.
> Runtime difference before vs after is within a noise.
> The number of processed instructions stays the same.
> 
> Signed-off-by: Alexei Starovoitov <ast@...nel.org>
> Acked-by: Daniel Borkmann <daniel@...earbox.net>

Applied, thanks Alexei.