bpf.vger.kernel.org archive mirror
 help / color / mirror / Atom feed
From: Paolo Abeni <pabeni@redhat.com>
To: Alexei Starovoitov <alexei.starovoitov@gmail.com>,
	Jakub Sitnicki <jakub@cloudflare.com>
Cc: bpf <bpf@vger.kernel.org>,
	Network Development <netdev@vger.kernel.org>,
	kernel-team <kernel-team@cloudflare.com>,
	Alexei Starovoitov <ast@kernel.org>,
	Daniel Borkmann <daniel@iogearbox.net>,
	"David S. Miller" <davem@davemloft.net>,
	Jakub Kicinski <kuba@kernel.org>,
	Andrii Nakryiko <andriin@fb.com>,
	Lorenz Bauer <lmb@cloudflare.com>,
	Marek Majkowski <marek@cloudflare.com>,
	Martin KaFai Lau <kafai@fb.com>, Yonghong Song <yhs@fb.com>
Subject: Re: BPF sk_lookup v5 - TCP SYN and UDP 0-len flood benchmarks
Date: Mon, 24 Aug 2020 10:17:03 +0200	[thread overview]
Message-ID: <8ccf0b77c854a20f65026fdc68dcd64b93d07fc5.camel@redhat.com> (raw)
In-Reply-To: <CAADnVQKE6y9h2fwX6OS837v-Uf+aBXnT_JXiN_bbo2gitZQ3tA@mail.gmail.com>

On Tue, 2020-08-18 at 11:19 -0700, Alexei Starovoitov wrote:
> On Tue, Aug 18, 2020 at 8:49 AM Jakub Sitnicki <jakub@cloudflare.com> wrote:
> >          :                      rcu_read_lock();
> >          :                      run_array = rcu_dereference(net->bpf.run_array[NETNS_BPF_SK_LOOKUP]);
> >     0.01 :   ffffffff817f8624:       mov    0xd68(%r12),%rsi
> >          :                      if (run_array) {
> >     0.00 :   ffffffff817f862c:       test   %rsi,%rsi
> >     0.00 :   ffffffff817f862f:       je     ffffffff817f87a9 <__udp4_lib_lookup+0x2c9>
> >          :                      struct bpf_sk_lookup_kern ctx = {
> >     1.05 :   ffffffff817f8635:       xor    %eax,%eax
> >     0.00 :   ffffffff817f8637:       mov    $0x6,%ecx
> >     0.01 :   ffffffff817f863c:       movl   $0x110002,0x40(%rsp)
> >     0.00 :   ffffffff817f8644:       lea    0x48(%rsp),%rdi
> >    18.76 :   ffffffff817f8649:       rep stos %rax,%es:(%rdi)
> >     1.12 :   ffffffff817f864c:       mov    0xc(%rsp),%eax
> >     0.00 :   ffffffff817f8650:       mov    %ebp,0x48(%rsp)
> >     0.00 :   ffffffff817f8654:       mov    %eax,0x44(%rsp)
> >     0.00 :   ffffffff817f8658:       movzwl 0x10(%rsp),%eax
> >     1.21 :   ffffffff817f865d:       mov    %ax,0x60(%rsp)
> >     0.00 :   ffffffff817f8662:       movzwl 0x20(%rsp),%eax
> >     0.00 :   ffffffff817f8667:       mov    %ax,0x62(%rsp)
> >          :                      .sport          = sport,
> >          :                      .dport          = dport,
> >          :                      };
> 
> Such heavy hit to zero init 56-byte structure is surprising.
> There are two 4-byte holes in this struct. You can try to pack it and
> make sure that 'rep stoq' is used instead of 'rep stos' (8 byte at a time vs 4).

I think here rep stos is copying 8 bytes at a time (%rax operand, %ecx
initalized with '6').

I think that you can avoid the costly instruction explicitly
initializing each field individually:

	struct bpf_sk_lookup_kern ctx;

	ctx.family = AF_INET;
	ctx.protocol = protocol;
	// ...

note, you likely want to explicitly zero the v6 addresses, too.

Cheers,

Paolo


      parent reply	other threads:[~2020-08-24  8:17 UTC|newest]

Thread overview: 32+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-07-17 10:35 [PATCH bpf-next v5 00/15] Run a BPF program on socket lookup Jakub Sitnicki
2020-07-17 10:35 ` [PATCH bpf-next v5 01/15] bpf, netns: Handle multiple link attachments Jakub Sitnicki
2020-07-17 10:35 ` [PATCH bpf-next v5 02/15] bpf: Introduce SK_LOOKUP program type with a dedicated attach point Jakub Sitnicki
2020-07-17 10:35 ` [PATCH bpf-next v5 03/15] inet: Extract helper for selecting socket from reuseport group Jakub Sitnicki
2020-07-17 10:35 ` [PATCH bpf-next v5 04/15] inet: Run SK_LOOKUP BPF program on socket lookup Jakub Sitnicki
2020-07-17 10:35 ` [PATCH bpf-next v5 05/15] inet6: Extract helper for selecting socket from reuseport group Jakub Sitnicki
2020-07-17 10:35 ` [PATCH bpf-next v5 06/15] inet6: Run SK_LOOKUP BPF program on socket lookup Jakub Sitnicki
2020-07-17 10:35 ` [PATCH bpf-next v5 07/15] udp: Extract helper for selecting socket from reuseport group Jakub Sitnicki
2020-07-17 10:35 ` [PATCH bpf-next v5 08/15] udp: Run SK_LOOKUP BPF program on socket lookup Jakub Sitnicki
2020-07-17 10:35 ` [PATCH bpf-next v5 09/15] udp6: Extract helper for selecting socket from reuseport group Jakub Sitnicki
2020-07-17 10:35 ` [PATCH bpf-next v5 10/15] udp6: Run SK_LOOKUP BPF program on socket lookup Jakub Sitnicki
2020-07-17 10:35 ` [PATCH bpf-next v5 11/15] bpf: Sync linux/bpf.h to tools/ Jakub Sitnicki
2020-07-17 10:35 ` [PATCH bpf-next v5 12/15] libbpf: Add support for SK_LOOKUP program type Jakub Sitnicki
2020-07-17 10:35 ` [PATCH bpf-next v5 13/15] tools/bpftool: Add name mappings for SK_LOOKUP prog and attach type Jakub Sitnicki
2020-07-17 10:35 ` [PATCH bpf-next v5 14/15] selftests/bpf: Add verifier tests for bpf_sk_lookup context access Jakub Sitnicki
2020-07-17 10:35 ` [PATCH bpf-next v5 15/15] selftests/bpf: Tests for BPF_SK_LOOKUP attach point Jakub Sitnicki
2020-07-28 20:13   ` Andrii Nakryiko
2020-07-28 20:47     ` Daniel Borkmann
2020-07-29  8:55       ` Jakub Sitnicki
2020-07-31  0:04         ` Daniel Borkmann
2020-07-29  8:57     ` Jakub Sitnicki
2020-07-30 13:10       ` Jakub Sitnicki
2020-07-30 19:43         ` Andrii Nakryiko
2020-07-17 16:40 ` [PATCH bpf-next v5 00/15] Run a BPF program on socket lookup Lorenz Bauer
2020-07-18  3:25   ` Alexei Starovoitov
2020-08-18 15:49 ` BPF sk_lookup v5 - TCP SYN and UDP 0-len flood benchmarks Jakub Sitnicki
2020-08-18 18:19   ` Alexei Starovoitov
2020-08-20 10:29     ` Jakub Sitnicki
2020-08-20 12:20       ` David Laight
2020-08-20 22:18       ` Alexei Starovoitov
2020-08-21 10:22         ` Jakub Sitnicki
2020-08-24  8:17     ` Paolo Abeni [this message]

Reply instructions:

You may reply publicly to this message via plain-text email
using any one of the following methods:

* Save the following mbox file, import it into your mail client,
  and reply-to-all from there: mbox

  Avoid top-posting and favor interleaved quoting:
  https://en.wikipedia.org/wiki/Posting_style#Interleaved_style

* Reply using the --to, --cc, and --in-reply-to
  switches of git-send-email(1):

  git send-email \
    --in-reply-to=8ccf0b77c854a20f65026fdc68dcd64b93d07fc5.camel@redhat.com \
    --to=pabeni@redhat.com \
    --cc=alexei.starovoitov@gmail.com \
    --cc=andriin@fb.com \
    --cc=ast@kernel.org \
    --cc=bpf@vger.kernel.org \
    --cc=daniel@iogearbox.net \
    --cc=davem@davemloft.net \
    --cc=jakub@cloudflare.com \
    --cc=kafai@fb.com \
    --cc=kernel-team@cloudflare.com \
    --cc=kuba@kernel.org \
    --cc=lmb@cloudflare.com \
    --cc=marek@cloudflare.com \
    --cc=netdev@vger.kernel.org \
    --cc=yhs@fb.com \
    /path/to/YOUR_REPLY

  https://kernel.org/pub/software/scm/git/docs/git-send-email.html

* If your mail client supports setting the In-Reply-To header
  via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line before the message body. 
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).