Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752789AbbBXFSp (ORCPT ); Tue, 24 Feb 2015 00:18:45 -0500 Received: from mail-lb0-f177.google.com ([209.85.217.177]:38575 "EHLO mail-lb0-f177.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750701AbbBXFSn (ORCPT ); Tue, 24 Feb 2015 00:18:43 -0500 From: Alexander Drozdov To: "David S. Miller" , Daniel Borkmann , Eric Dumazet , Al Viro , Willem de Bruijn , "Michael S. Tsirkin" Cc: netdev@vger.kernel.org, linux-kernel@vger.kernel.org, Alexander Drozdov , Dan Collins , Guy Harris Subject: [RESEND PATCH] af_packet: don't pass empty blocks for PACKET_V3 Date: Tue, 24 Feb 2015 08:18:28 +0300 Message-Id: <1424755108-10493-1-git-send-email-al.drozdov@gmail.com> X-Mailer: git-send-email 1.9.1 In-Reply-To: <1423115891-3578-1-git-send-email-al.drozdov@gmail.com> References: <1423115891-3578-1-git-send-email-al.drozdov@gmail.com> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2085 Lines: 53 Before da413eec729d ("packet: Fixed TPACKET V3 to signal poll when block is closed rather than every packet") poll listening for an af_packet socket was not signaled if there was no packets to process. After the patch poll is signaled evety time when block retire timer expires. That happens because af_packet closes the current block on timeout even if the block is empty. Passing empty blocks to the user not only wastes CPU but also wastes ring buffer space increasing probability of packets dropping on small timeouts. Signed-off-by: Alexander Drozdov Cc: Dan Collins Cc: Willem de Bruijn Cc: Guy Harris --- net/packet/af_packet.c | 10 +++++++++- 1 file changed, 9 insertions(+), 1 deletion(-) diff --git a/net/packet/af_packet.c b/net/packet/af_packet.c index 9c28cec..1da46ef 100644 --- a/net/packet/af_packet.c +++ b/net/packet/af_packet.c @@ -698,6 +698,10 @@ static void prb_retire_rx_blk_timer_expired(unsigned long data) if (pkc->last_kactive_blk_num == pkc->kactive_blk_num) { if (!frozen) { + if (!BLOCK_NUM_PKTS(pbd)) { + /* An empty block. Just refresh the timer. */ + goto refresh_timer; + } prb_retire_current_block(pkc, po, TP_STATUS_BLK_TMO); if (!prb_dispatch_next_block(pkc, po)) goto refresh_timer; @@ -798,7 +802,11 @@ static void prb_close_block(struct tpacket_kbdq_core *pkc1, h1->ts_last_pkt.ts_sec = last_pkt->tp_sec; h1->ts_last_pkt.ts_nsec = last_pkt->tp_nsec; } else { - /* Ok, we tmo'd - so get the current time */ + /* Ok, we tmo'd - so get the current time. + * + * It shouldn't really happen as we don't close empty + * blocks. See prb_retire_rx_blk_timer_expired(). + */ struct timespec ts; getnstimeofday(&ts); h1->ts_last_pkt.ts_sec = ts.tv_sec; -- 1.9.1 -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/