diff options
| author |   Gerrit Renker <gerrit@erg.abdn.ac.uk> | 2006-12-10 00:02:12 -0200 |
|---|---|---|
| committer |   David S. Miller <davem@sunset.davemloft.net> | 2006-12-11 14:34:42 -0800 |
| commit | 1a21e49a8d60f588c1276f765198b14d5688a778 (patch) | |
| tree | 4b8770be71047437f30da694649719948977b189 /net/dccp/ccids/ccid3.h | |
| parent | [DCCP] ccid3: Fix two bugs in sending rate computation (diff) | |
| download | linux-dev-1a21e49a8d60f588c1276f765198b14d5688a778.tar.xz linux-dev-1a21e49a8d60f588c1276f765198b14d5688a778.zip | |
[DCCP] ccid3: Finer-grained resolution of sending rates
This patch
* resolves a bug where packets smaller than 32/64 bytes resulted in sending rates of 0
* supports all sending rates from 1/64 bytes/second up to 4Gbyte/second
* simplifies the present overflow problems in calculations
Current sending rate X and the cached value X_recv of the receiver-estimated
sending rate are both scaled by 64 (2^6) in order to
* cope with low sending rates (minimally 1 byte/second)
* allow upgrading to use a packets-per-second implementation of CCID 3
* avoid calculation errors due to integer arithmetic cut-off
The patch implements a revised strategy from
http://www.mail-archive.com/dccp@vger.kernel.org/msg01040.html
The only difference with regard to that strategy is that t_ipi is already
used in the calculation of the nofeedback timeout, which saves one division.
Signed-off-by: Gerrit Renker <gerrit@erg.abdn.ac.uk>
Acked-by: Ian McDonald <ian.mcdonald@jandi.co.nz>
Signed-off-by: Arnaldo Carvalho de Melo <acme@mandriva.com>
Diffstat (limited to 'net/dccp/ccids/ccid3.h')
| -rw-r--r-- | net/dccp/ccids/ccid3.h | 33 |
1 files changed, 26 insertions, 7 deletions
diff --git a/net/dccp/ccids/ccid3.h b/net/dccp/ccids/ccid3.h index 07596d704ef9..cd4fc542f73e 100644 --- a/net/dccp/ccids/ccid3.h +++ b/net/dccp/ccids/ccid3.h @@ -75,14 +75,14 @@ enum ccid3_hc_tx_states { /** struct ccid3_hc_tx_sock - CCID3 sender half-connection socket * - * @ccid3hctx_x - Current sending rate - * @ccid3hctx_x_recv - Receive rate - * @ccid3hctx_x_calc - Calculated send rate (RFC 3448, 3.1) + * @ccid3hctx_x - Current sending rate in 64 * bytes per second + * @ccid3hctx_x_recv - Receive rate in 64 * bytes per second + * @ccid3hctx_x_calc - Calculated rate in bytes per second * @ccid3hctx_rtt - Estimate of current round trip time in usecs * @ccid3hctx_p - Current loss event rate (0-1) scaled by 1000000 - * @ccid3hctx_s - Packet size - * @ccid3hctx_t_rto - Retransmission Timeout (RFC 3448, 3.1) - * @ccid3hctx_t_ipi - Interpacket (send) interval (RFC 3448, 4.6) + * @ccid3hctx_s - Packet size in bytes + * @ccid3hctx_t_rto - Nofeedback Timer setting in usecs + * @ccid3hctx_t_ipi - Interpacket (send) interval (RFC 3448, 4.6) in usecs * @ccid3hctx_state - Sender state, one of %ccid3_hc_tx_states * @ccid3hctx_last_win_count - Last window counter sent * @ccid3hctx_t_last_win_count - Timestamp of earliest packet @@ -91,7 +91,7 @@ enum ccid3_hc_tx_states { * @ccid3hctx_idle - Flag indicating that sender is idling * @ccid3hctx_t_ld - Time last doubled during slow start * @ccid3hctx_t_nom - Nominal send time of next packet - * @ccid3hctx_delta - Send timer delta + * @ccid3hctx_delta - Send timer delta (RFC 3448, 4.6) in usecs * @ccid3hctx_hist - Packet history * @ccid3hctx_options_received - Parsed set of retrieved options */ @@ -171,4 +171,23 @@ static inline struct ccid3_hc_rx_sock *ccid3_hc_rx_sk(const struct sock *sk) return ccid_priv(dccp_sk(sk)->dccps_hc_rx_ccid); } +static inline u64 scaled_div(u64 a, u32 b) +{ + BUG_ON(b==0); + a *= 1000000; + do_div(a, b); + return a; +} + +static inline u32 scaled_div32(u64 a, u32 b) +{ + u64 result = scaled_div(a, b); + + if (result > UINT_MAX) { + DCCP_CRIT("Overflow: a(%llu)/b(%u) > ~0U", + (unsigned long long)a, b); + return UINT_MAX; + } + return result; +} #endif /* _DCCP_CCID3_H_ */ |