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Date: Thu, 28 Aug 2008 18:26:30 -0300
From: Arnaldo Carvalho de Melo <acme@...hat.com>
To: Gerrit Renker <gerrit@....abdn.ac.uk>
Cc: dccp@...r.kernel.org, netdev@...r.kernel.org
Subject: Re: [PATCH 13/37] dccp: Deprecate Ack Ratio sysctl
Em Thu, Aug 28, 2008 at 07:44:48PM +0200, Gerrit Renker escreveu:
> This patch deprecates the Ack Ratio sysctl, since
> * Ack Ratio is entirely ignored by CCID-3 and CCID-4,
> * Ack Ratio currently doesn't work in CCID-2 (i.e. is always set to 1);
> * even if it would work in CCID-2, there is no point for a user to change it:
> - Ack Ratio is constrained by cwnd (RFC 4341, 6.1.2),
> - if Ack Ratio > cwnd, the system resorts to spurious RTO timeouts
> (since waiting for Acks which will never arrive in this window),
> - cwnd is not a user-configurable value.
>
> The only reasonable place for Ack Ratio is to print it for debugging. It is
> planned to do this later on, as part of e.g. dccp_probe.
>
> With this patch Ack Ratio is now under full control of feature negotiation:
> * Ack Ratio is resolved as a dependency of the selected CCID;
> * if the chosen CCID supports it (i.e. CCID == CCID-2), Ack Ratio is set to
> the default of 2, following RFC 4340, 11.3 - "New connections start with Ack
> Ratio 2 for both endpoints";
> * what happens then is part of another patch set, since it concerns the
> dynamic update of Ack Ratio while the connection is in full flight.
>
> Thanks to Tomasz Grobelny for discussion leading up to this patch.
>
> Signed-off-by: Gerrit Renker <gerrit@....abdn.ac.uk>
Looks ok,
Acked-by: Arnaldo Carvalho de Melo <acme@...hat.com>
> ---
> Documentation/networking/dccp.txt | 3 ---
> include/linux/dccp.h | 2 --
> net/dccp/dccp.h | 1 -
> net/dccp/minisocks.c | 1 -
> net/dccp/options.c | 1 -
> net/dccp/sysctl.c | 7 -------
> 6 files changed, 0 insertions(+), 15 deletions(-)
>
> --- a/Documentation/networking/dccp.txt
> +++ b/Documentation/networking/dccp.txt
> @@ -125,9 +125,6 @@ send_ndp = 1
> send_ackvec = 1
> Whether or not to send Ack Vector options (sec. 11.5).
>
> -ack_ratio = 2
> - The default Ack Ratio (sec. 11.3) to use.
> -
> tx_ccid = 2
> Default CCID for the sender-receiver half-connection.
>
> --- a/include/linux/dccp.h
> +++ b/include/linux/dccp.h
> @@ -368,7 +368,6 @@ static inline unsigned int dccp_hdr_len(const struct sk_buff *skb)
> * @dccpms_ccid - Congestion Control Id (CCID) (section 10)
> * @dccpms_send_ack_vector - Send Ack Vector Feature (section 11.5)
> * @dccpms_send_ndp_count - Send NDP Count Feature (7.7.2)
> - * @dccpms_ack_ratio - Ack Ratio Feature (section 11.3)
> * @dccpms_pending - List of features being negotiated
> * @dccpms_conf -
> */
> @@ -378,7 +377,6 @@ struct dccp_minisock {
> __u8 dccpms_tx_ccid;
> __u8 dccpms_send_ack_vector;
> __u8 dccpms_send_ndp_count;
> - __u8 dccpms_ack_ratio;
> struct list_head dccpms_pending;
> struct list_head dccpms_conf;
> };
> --- a/net/dccp/dccp.h
> +++ b/net/dccp/dccp.h
> @@ -98,7 +98,6 @@ extern int sysctl_dccp_retries2;
> extern int sysctl_dccp_feat_sequence_window;
> extern int sysctl_dccp_feat_rx_ccid;
> extern int sysctl_dccp_feat_tx_ccid;
> -extern int sysctl_dccp_feat_ack_ratio;
> extern int sysctl_dccp_feat_send_ack_vector;
> extern int sysctl_dccp_feat_send_ndp_count;
> extern int sysctl_dccp_tx_qlen;
> --- a/net/dccp/minisocks.c
> +++ b/net/dccp/minisocks.c
> @@ -47,7 +47,6 @@ void dccp_minisock_init(struct dccp_minisock *dmsk)
> dmsk->dccpms_sequence_window = sysctl_dccp_feat_sequence_window;
> dmsk->dccpms_rx_ccid = sysctl_dccp_feat_rx_ccid;
> dmsk->dccpms_tx_ccid = sysctl_dccp_feat_tx_ccid;
> - dmsk->dccpms_ack_ratio = sysctl_dccp_feat_ack_ratio;
> dmsk->dccpms_send_ack_vector = sysctl_dccp_feat_send_ack_vector;
> dmsk->dccpms_send_ndp_count = sysctl_dccp_feat_send_ndp_count;
> }
> --- a/net/dccp/options.c
> +++ b/net/dccp/options.c
> @@ -26,7 +26,6 @@
> int sysctl_dccp_feat_sequence_window = DCCPF_INITIAL_SEQUENCE_WINDOW;
> int sysctl_dccp_feat_rx_ccid = DCCPF_INITIAL_CCID;
> int sysctl_dccp_feat_tx_ccid = DCCPF_INITIAL_CCID;
> -int sysctl_dccp_feat_ack_ratio = DCCPF_INITIAL_ACK_RATIO;
> int sysctl_dccp_feat_send_ack_vector = DCCPF_INITIAL_SEND_ACK_VECTOR;
> int sysctl_dccp_feat_send_ndp_count = DCCPF_INITIAL_SEND_NDP_COUNT;
>
> --- a/net/dccp/sysctl.c
> +++ b/net/dccp/sysctl.c
> @@ -41,13 +41,6 @@ static struct ctl_table dccp_default_table[] = {
> .proc_handler = proc_dointvec,
> },
> {
> - .procname = "ack_ratio",
> - .data = &sysctl_dccp_feat_ack_ratio,
> - .maxlen = sizeof(sysctl_dccp_feat_ack_ratio),
> - .mode = 0644,
> - .proc_handler = proc_dointvec,
> - },
> - {
> .procname = "send_ackvec",
> .data = &sysctl_dccp_feat_send_ack_vector,
> .maxlen = sizeof(sysctl_dccp_feat_send_ack_vector),
> --
> 1.6.0.rc2
>
> --
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