From nobody Sat Oct 4 19:16:42 2025 Received: from m16.mail.163.com (m16.mail.163.com [220.197.31.3]) by smtp.subspace.kernel.org (Postfix) with ESMTP id DE794246BC1; Wed, 13 Aug 2025 16:52:43 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=220.197.31.3 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1755103968; cv=none; b=TVR4ba10Wv5DDskItyn1Qn7C9RFVWJxXnNhP77GLVjqLIQqBxWzqYuidQKJ1+7w9Z4wWEYKmrdLQGcEBf6OKuzVwVeiN9aCVZ2lSB6npXc6Gr81se8uxaJ+5AK6jIoRB2wUpRQ3HOK2MSu4iKrHICbADmWLWOHE+csJgDso2aSA= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1755103968; c=relaxed/simple; bh=9QCc3j7Nu7J1rYdLuLDu6Gu2I3KvelaAd4J5+ojVcH8=; h=From:To:Cc:Subject:Date:Message-Id:MIME-Version; b=qUJaJEg1+AqdYR3K0zfNW0kn+vKfOyqe9OeL6C1iCLPjoqGRNsse83o7ccQM7LHrAapntr9SPdV5RphPiSdGIchjEMu5mdATC+QlLhLJU8jnZtN48IJ59hkb63pWW8ygG977t7E932YefzdeyyyHWnvF5MqhgeS+sNNg5YrHzsQ= ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=163.com; spf=pass smtp.mailfrom=163.com; dkim=pass (1024-bit key) header.d=163.com header.i=@163.com header.b=iXNi7r2k; arc=none smtp.client-ip=220.197.31.3 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=163.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=163.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=163.com header.i=@163.com header.b="iXNi7r2k" DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=163.com; s=s110527; h=From:To:Subject:Date:Message-Id:MIME-Version; bh=6d ZW97DLwK3hq4Qvj+4tZMAjOl8ZsoVPuweEcUtDLR8=; b=iXNi7r2kHIUX+TZkAC yTdlUXN8I7ZVG9uZKthyOK9g2AsL/+GOCg3aFWltubkzMVmrELSl7/phTWaiQapN flRvTw4EYZy0ru0iku7HR+cITB/ToPW9QoybaZe+jJY0Go8V4fNSfjAUYAlz6nuj yXjh8A6qNqbTTjzkPi9GBLCVg= Received: from zhaoxin-MS-7E12.. (unknown []) by gzga-smtp-mtada-g1-1 (Coremail) with SMTP id _____wD3f9Czwpxooy_tBA--.18339S2; Thu, 14 Aug 2025 00:52:04 +0800 (CST) From: Xin Zhao To: willemdebruijn.kernel@gmail.com, edumazet@google.com, ferenc@fejes.dev Cc: davem@davemloft.net, kuba@kernel.org, pabeni@redhat.com, horms@kernel.org, netdev@vger.kernel.org, linux-kernel@vger.kernel.org, Xin Zhao Subject: [PATCH v1] net: af_packet: Use hrtimer to do the retire operation Date: Thu, 14 Aug 2025 00:52:01 +0800 Message-Id: <20250813165201.1492779-1-jackzxcui1989@163.com> X-Mailer: git-send-email 2.34.1 Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable X-CM-TRANSID: _____wD3f9Czwpxooy_tBA--.18339S2 X-Coremail-Antispam: 1Uf129KBjvJXoWxXw1rAr1kWF4UJF1DXw47Arb_yoWrtF4fpa y5W34xGw47Za1agw48Xrs7ZFyYgw1DAry7G393Xwsay3Z3try5ta1j9Fyq9FWftFZFkw43 Ar4ktFs8Cw1kXrDanT9S1TB71UUUUU7qnTZGkaVYY2UrUUUUjbIjqfuFe4nvWSU5nxnvy2 9KBjDUYxBIdaVFxhVjvjDU0xZFpf9x0pEy8BnUUUUU= X-CM-SenderInfo: pmdfy650fxxiqzyzqiywtou0bp/1tbiRwqoCmicsxzwmwAAsf Content-Type: text/plain; charset="utf-8" In a system with high real-time requirements, the timeout mechanism of ordinary timers with jiffies granularity is insufficient to meet the demands for real-time performance. Meanwhile, the optimization of CPU usage with af_packet is quite significant. Use hrtimer instead of timer to help compensate for the shortcomings in real-time performance. In HZ=3D100 or HZ=3D250 system, the update of TP_STATUS_USER is not real-ti= me enough, with fluctuations reaching over 8ms (on a system with HZ=3D250). This is unacceptable in some high real-time systems that require timely processing of network packets. By replacing it with hrtimer, if a timeout of 2ms is set, the update of TP_STATUS_USER can be stabilized to within 3 ms. Signed-off-by: Xin Zhao --- net/packet/af_packet.c | 20 +++++++++++--------- net/packet/internal.h | 4 ++-- 2 files changed, 13 insertions(+), 11 deletions(-) diff --git a/net/packet/af_packet.c b/net/packet/af_packet.c index bc438d0d9..636b72bf6 100644 --- a/net/packet/af_packet.c +++ b/net/packet/af_packet.c @@ -203,7 +203,7 @@ static void prb_retire_current_block(struct tpacket_kbd= q_core *, static int prb_queue_frozen(struct tpacket_kbdq_core *); static void prb_open_block(struct tpacket_kbdq_core *, struct tpacket_block_desc *); -static void prb_retire_rx_blk_timer_expired(struct timer_list *); +static enum hrtimer_restart prb_retire_rx_blk_timer_expired(struct hrtimer= *); static void _prb_refresh_rx_retire_blk_timer(struct tpacket_kbdq_core *); static void prb_fill_rxhash(struct tpacket_kbdq_core *, struct tpacket3_hd= r *); static void prb_clear_rxhash(struct tpacket_kbdq_core *, @@ -581,7 +581,7 @@ static __be16 vlan_get_protocol_dgram(const struct sk_b= uff *skb) =20 static void prb_del_retire_blk_timer(struct tpacket_kbdq_core *pkc) { - timer_delete_sync(&pkc->retire_blk_timer); + hrtimer_cancel(&pkc->retire_blk_timer); } =20 static void prb_shutdown_retire_blk_timer(struct packet_sock *po, @@ -603,9 +603,10 @@ static void prb_setup_retire_blk_timer(struct packet_s= ock *po) struct tpacket_kbdq_core *pkc; =20 pkc =3D GET_PBDQC_FROM_RB(&po->rx_ring); - timer_setup(&pkc->retire_blk_timer, prb_retire_rx_blk_timer_expired, - 0); - pkc->retire_blk_timer.expires =3D jiffies; + hrtimer_setup(&pkc->retire_blk_timer, prb_retire_rx_blk_timer_expired, + CLOCK_MONOTONIC, HRTIMER_MODE_REL_SOFT); + hrtimer_start(&pkc->retire_blk_timer, ms_to_ktime(pkc->tov_in_msecs), + HRTIMER_MODE_REL_SOFT); } =20 static int prb_calc_retire_blk_tmo(struct packet_sock *po, @@ -676,7 +677,7 @@ static void init_prb_bdqc(struct packet_sock *po, else p1->retire_blk_tov =3D prb_calc_retire_blk_tmo(po, req_u->req3.tp_block_size); - p1->tov_in_jiffies =3D msecs_to_jiffies(p1->retire_blk_tov); + p1->tov_in_msecs =3D p1->retire_blk_tov; p1->blk_sizeof_priv =3D req_u->req3.tp_sizeof_priv; rwlock_init(&p1->blk_fill_in_prog_lock); =20 @@ -691,8 +692,8 @@ static void init_prb_bdqc(struct packet_sock *po, */ static void _prb_refresh_rx_retire_blk_timer(struct tpacket_kbdq_core *pkc) { - mod_timer(&pkc->retire_blk_timer, - jiffies + pkc->tov_in_jiffies); + hrtimer_set_expires(&pkc->retire_blk_timer, + ktime_add(ktime_get(), ms_to_ktime(pkc->tov_in_msecs))); pkc->last_kactive_blk_num =3D pkc->kactive_blk_num; } =20 @@ -719,7 +720,7 @@ static void _prb_refresh_rx_retire_blk_timer(struct tpa= cket_kbdq_core *pkc) * prb_calc_retire_blk_tmo() calculates the tmo. * */ -static void prb_retire_rx_blk_timer_expired(struct timer_list *t) +static enum hrtimer_restart prb_retire_rx_blk_timer_expired(struct hrtimer= *t) { struct packet_sock *po =3D timer_container_of(po, t, rx_ring.prb_bdqc.retire_blk_timer); @@ -790,6 +791,7 @@ static void prb_retire_rx_blk_timer_expired(struct time= r_list *t) =20 out: spin_unlock(&po->sk.sk_receive_queue.lock); + return HRTIMER_RESTART; } =20 static void prb_flush_block(struct tpacket_kbdq_core *pkc1, diff --git a/net/packet/internal.h b/net/packet/internal.h index 1e743d031..41df245e3 100644 --- a/net/packet/internal.h +++ b/net/packet/internal.h @@ -47,10 +47,10 @@ struct tpacket_kbdq_core { =20 unsigned short retire_blk_tov; unsigned short version; - unsigned long tov_in_jiffies; + unsigned long tov_in_msecs; =20 /* timer to retire an outstanding block */ - struct timer_list retire_blk_timer; + struct hrtimer retire_blk_timer; }; =20 struct pgv { --=20 2.34.1