From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from us-smtp-delivery-124.mimecast.com (us-smtp-delivery-124.mimecast.com [170.10.133.124]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 4225516EBE7 for ; Mon, 1 Jul 2024 18:10:45 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=170.10.133.124 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1719857447; cv=none; b=Bjv2NT3C3XgpshWT3qNC3SgoaxABeTbcmCywjonFQZIwWyvPrq6E0A5qI6QUT0J3Sh0pe8iTpqLmbnsePj/1+72tGW2Qm14zhDt/Jgv/HAE2w/I3PIaxhGFb0uirhQg3xLsyEMCmFtXYc7TruTYFdaSe+yGbo7BMX0rpzSRddgE= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1719857447; c=relaxed/simple; bh=ub7wy9wbVGLRWhSD/YbjKzEHraTvzBQPoST6f7ZZa6k=; h=From:To:Cc:Subject:In-Reply-To:References:Date:Message-ID: MIME-Version:Content-Type; b=nhz7stiF8btH74cgqOD76+Mn1NCMQSM7avY+ROmt7/y/zB9X0Kn7ro5Sn0GuoZX587GSVINR5m0Ti8eAB9iJaTkOIoeJc2Jr6jp8pWKOE2esE6JgRHyPcj4an6HlsfDSBq9PDbVQTUZ2wouE4kA34UIrxF1CUNfPILB80ttD6X4= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=redhat.com; spf=pass smtp.mailfrom=redhat.com; dkim=pass (1024-bit key) header.d=redhat.com header.i=@redhat.com header.b=FFKlwTwH; arc=none smtp.client-ip=170.10.133.124 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=redhat.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=redhat.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=redhat.com header.i=@redhat.com header.b="FFKlwTwH" DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1719857445; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: in-reply-to:in-reply-to:references:references; bh=JM1W3lT8X94kstTVgU0L4T7iVYaF/txP6qsNDPjlfkI=; b=FFKlwTwHvEf+tAUeBJ3U3iFWEYa6ykFOXuiN5dsnWVOBIS13owPJcw0uHvLS3QsV/SXjHI 3A/8R8FWOGF7h59w0XRuPaQK6ZzLAXYTBIkDSI7awu3wNmLh1Jel5JLwriPP49Nan9jbDh VhrfjILFHAwx5YiDLvyFhw2YXeuJvcQ= Received: from mx-prod-mc-02.mail-002.prod.us-west-2.aws.redhat.com (ec2-54-186-198-63.us-west-2.compute.amazonaws.com [54.186.198.63]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.3, cipher=TLS_AES_256_GCM_SHA384) id us-mta-382-HmKSMqD2MvqWr_YFd2CCXg-1; Mon, 01 Jul 2024 14:10:42 -0400 X-MC-Unique: HmKSMqD2MvqWr_YFd2CCXg-1 Received: from mx-prod-int-03.mail-002.prod.us-west-2.aws.redhat.com (mx-prod-int-03.mail-002.prod.us-west-2.aws.redhat.com [10.30.177.12]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature RSA-PSS (2048 bits) server-digest SHA256) (No client certificate requested) by mx-prod-mc-02.mail-002.prod.us-west-2.aws.redhat.com (Postfix) with ESMTPS id E74CC1955DCD; Mon, 1 Jul 2024 18:10:39 +0000 (UTC) Received: from RHTRH0061144 (unknown [10.22.8.184]) by mx-prod-int-03.mail-002.prod.us-west-2.aws.redhat.com (Postfix) with ESMTPS id 9332A19560AE; Mon, 1 Jul 2024 18:10:36 +0000 (UTC) From: Aaron Conole To: Adrian Moreno Cc: netdev@vger.kernel.org, echaudro@redhat.com, horms@kernel.org, i.maximets@ovn.org, dev@openvswitch.org, Ido Schimmel , Yotam Gigi , "David S. Miller" , Eric Dumazet , Jakub Kicinski , Paolo Abeni , linux-kernel@vger.kernel.org Subject: Re: [PATCH net-next v7 04/10] net: psample: allow using rate as probability In-Reply-To: <20240630195740.1469727-5-amorenoz@redhat.com> (Adrian Moreno's message of "Sun, 30 Jun 2024 21:57:25 +0200") References: <20240630195740.1469727-1-amorenoz@redhat.com> <20240630195740.1469727-5-amorenoz@redhat.com> Date: Mon, 01 Jul 2024 14:10:34 -0400 Message-ID: User-Agent: Gnus/5.13 (Gnus v5.13) Precedence: bulk X-Mailing-List: netdev@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain X-Scanned-By: MIMEDefang 3.0 on 10.30.177.12 Adrian Moreno writes: > Although not explicitly documented in the psample module itself, the > definition of PSAMPLE_ATTR_SAMPLE_RATE seems inherited from act_sample. > > Quoting tc-sample(8): > "RATE of 100 will lead to an average of one sampled packet out of every > 100 observed." > > With this semantics, the rates that we can express with an unsigned > 32-bits number are very unevenly distributed and concentrated towards > "sampling few packets". > For example, we can express a probability of 2.32E-8% but we > cannot express anything between 100% and 50%. > > For sampling applications that are capable of sampling a decent > amount of packets, this sampling rate semantics is not very useful. > > Add a new flag to the uAPI that indicates that the sampling rate is > expressed in scaled probability, this is: > - 0 is 0% probability, no packets get sampled. > - U32_MAX is 100% probability, all packets get sampled. > > Acked-by: Eelco Chaudron > Reviewed-by: Ido Schimmel > Signed-off-by: Adrian Moreno > --- Reviewed-by: Aaron Conole > include/net/psample.h | 3 ++- > include/uapi/linux/psample.h | 10 +++++++++- > net/psample/psample.c | 3 +++ > 3 files changed, 14 insertions(+), 2 deletions(-) > > diff --git a/include/net/psample.h b/include/net/psample.h > index 2ac71260a546..c52e9ebd88dd 100644 > --- a/include/net/psample.h > +++ b/include/net/psample.h > @@ -24,7 +24,8 @@ struct psample_metadata { > u8 out_tc_valid:1, > out_tc_occ_valid:1, > latency_valid:1, > - unused:5; > + rate_as_probability:1, > + unused:4; > const u8 *user_cookie; > u32 user_cookie_len; > }; > diff --git a/include/uapi/linux/psample.h b/include/uapi/linux/psample.h > index e80637e1d97b..b765f0e81f20 100644 > --- a/include/uapi/linux/psample.h > +++ b/include/uapi/linux/psample.h > @@ -8,7 +8,11 @@ enum { > PSAMPLE_ATTR_ORIGSIZE, > PSAMPLE_ATTR_SAMPLE_GROUP, > PSAMPLE_ATTR_GROUP_SEQ, > - PSAMPLE_ATTR_SAMPLE_RATE, > + PSAMPLE_ATTR_SAMPLE_RATE, /* u32, ratio between observed and > + * sampled packets or scaled probability > + * if PSAMPLE_ATTR_SAMPLE_PROBABILITY > + * is set. > + */ > PSAMPLE_ATTR_DATA, > PSAMPLE_ATTR_GROUP_REFCOUNT, > PSAMPLE_ATTR_TUNNEL, > @@ -20,6 +24,10 @@ enum { > PSAMPLE_ATTR_TIMESTAMP, /* u64, nanoseconds */ > PSAMPLE_ATTR_PROTO, /* u16 */ > PSAMPLE_ATTR_USER_COOKIE, /* binary, user provided data */ > + PSAMPLE_ATTR_SAMPLE_PROBABILITY,/* no argument, interpret rate in > + * PSAMPLE_ATTR_SAMPLE_RATE as a > + * probability scaled 0 - U32_MAX. > + */ > > __PSAMPLE_ATTR_MAX > }; > diff --git a/net/psample/psample.c b/net/psample/psample.c > index 1c76f3e48dcd..f48b5b9cd409 100644 > --- a/net/psample/psample.c > +++ b/net/psample/psample.c > @@ -497,6 +497,9 @@ void psample_sample_packet(struct psample_group *group, struct sk_buff *skb, > md->user_cookie)) > goto error; > > + if (md->rate_as_probability) > + nla_put_flag(skb, PSAMPLE_ATTR_SAMPLE_PROBABILITY); > + > genlmsg_end(nl_skb, data); > genlmsg_multicast_netns(&psample_nl_family, group->net, nl_skb, 0, > PSAMPLE_NL_MCGRP_SAMPLE, GFP_ATOMIC);