[{"id":1787051,"web_url":"http://patchwork.ozlabs.org/comment/1787051/","msgid":"<1508088729.31614.66.camel@edumazet-glaptop3.roam.corp.google.com>","list_archive_url":null,"date":"2017-10-15T17:32:09","subject":"Re: [RFC PATCH v2 3/5] tcp: added get_segs_per_round","submitter":{"id":2404,"url":"http://patchwork.ozlabs.org/api/people/2404/","name":"Eric Dumazet","email":"eric.dumazet@gmail.com"},"content":"On Sat, 2017-10-14 at 13:47 +0200, Natale Patriciello wrote:\n> Usually, the pacing time is provided per-segment. In some occasion, this\n> time refers to the time between a group of segments. With this commit, add\n> the possibility for the congestion control module to tell the TCP socket\n> how many segments can be sent out before pausing and setting a pacing\n> timer.\n> \n> Signed-off-by: Natale Patriciello \n> ---\n> include/net/tcp.h | 2 ++\n> net/ipv4/tcp_output.c | 13 +++++++++----\n> 2 files changed, 11 insertions(+), 4 deletions(-)\n> \n> diff --git a/include/net/tcp.h b/include/net/tcp.h\n> index e817f0669d0e..3561eca5a61f 100644\n> --- a/include/net/tcp.h\n> +++ b/include/net/tcp.h\n> @@ -1019,6 +1019,8 @@ struct tcp_congestion_ops {\n> \tu64 (*get_pacing_time)(struct sock *sk);\n> \t/* the pacing timer is expired (optional) */\n> \tvoid (*pacing_timer_expired)(struct sock *sk);\n> +\t/* get the # segs to send out when the timer expires (optional) */\n> +\tu32 (*get_segs_per_round)(struct sock *sk);\n> \n> \tchar \t\tname[TCP_CA_NAME_MAX];\n> \tstruct module \t*owner;\n> diff --git a/net/ipv4/tcp_output.c b/net/ipv4/tcp_output.c\n> index 25b4cf0802f2..e37941e4328b 100644\n> --- a/net/ipv4/tcp_output.c\n> +++ b/net/ipv4/tcp_output.c\n> @@ -2249,6 +2249,7 @@ static bool tcp_write_xmit(struct sock *sk, unsigned int mss_now, int nonagle,\n> \tint result;\n> \tbool is_cwnd_limited = false, is_rwnd_limited = false;\n> \tu32 max_segs;\n> +\tu32 pacing_allowed_segs = 0;\n> \n> \tsent_pkts = 0;\n> \n> @@ -2265,14 +2266,18 @@ static bool tcp_write_xmit(struct sock *sk, unsigned int mss_now, int nonagle,\n> \tmax_segs = tcp_tso_segs(sk, mss_now);\n> \ttcp_mstamp_refresh(tp);\n> \n> -\tif (!tcp_pacing_timer_check(sk) &&\n> -\t ca_ops && ca_ops->pacing_timer_expired)\n> -\t\tca_ops->pacing_timer_expired(sk);\n> +\tif (!tcp_pacing_timer_check(sk)) {\n> +\t\tpacing_allowed_segs = 1;\n> +\t\tif (ca_ops && ca_ops->pacing_timer_expired)\n> +\t\t\tca_ops->pacing_timer_expired(sk);\n> +\t\tif (ca_ops && ca_ops->get_segs_per_round)\n> +\t\t\tpacing_allowed_segs = ca_ops->get_segs_per_round(sk);\n> +\t}\n> \n> \twhile ((skb = tcp_send_head(sk))) {\n> \t\tunsigned int limit;\n> \n> -\t\tif (tcp_pacing_check(sk))\n> +\t\tif (sent_pkts >= pacing_allowed_segs)\n> \t\t\tbreak;\n> \n\nSo, if pacing_allowed_segs == 0, we break immediately of the loop ????\n\nAre you sure you have tested this patch with normal CC like CUBIC and\nBBR ?","headers":{"Return-Path":"","X-Original-To":"patchwork-incoming@ozlabs.org","Delivered-To":"patchwork-incoming@ozlabs.org","Authentication-Results":["ozlabs.org;\n\tspf=none (mailfrom) smtp.mailfrom=vger.kernel.org\n\t(client-ip=209.132.180.67; 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Miller\" ,\n\tnetdev , Ahmed Said ,\n\tFrancesco Zampognaro ,\n\tCesare Roseti ","Date":"Sun, 15 Oct 2017 10:32:09 -0700","In-Reply-To":"<20171014114714.3694-4-natale.patriciello@gmail.com>","References":"<20171014114714.3694-1-natale.patriciello@gmail.com>\n\t<20171014114714.3694-4-natale.patriciello@gmail.com>","Content-Type":"text/plain; charset=\"UTF-8\"","X-Mailer":"Evolution 3.10.4-0ubuntu2 ","Mime-Version":"1.0","Content-Transfer-Encoding":"7bit","Sender":"netdev-owner@vger.kernel.org","Precedence":"bulk","List-ID":"","X-Mailing-List":"netdev@vger.kernel.org"}}]