diff options
| author | Gerrit Renker <gerrit@erg.abdn.ac.uk> | 2006-12-10 05:02:12 +0300 |
|---|---|---|
| committer | David S. Miller <davem@sunset.davemloft.net> | 2006-12-12 01:34:42 +0300 |
| commit | 1a21e49a8d60f588c1276f765198b14d5688a778 (patch) | |
| tree | 4b8770be71047437f30da694649719948977b189 /include/linux/tfrc.h | |
| parent | 179ebc9f92da88e15ea86d7d27308c92712d8ee9 (diff) | |
| download | linux-1a21e49a8d60f588c1276f765198b14d5688a778.tar.xz | |
[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 'include/linux/tfrc.h')
| -rw-r--r-- | include/linux/tfrc.h | 8 |
1 files changed, 6 insertions, 2 deletions
diff --git a/include/linux/tfrc.h b/include/linux/tfrc.h index 31a9b25276fe..8a8462b4a4dd 100644 --- a/include/linux/tfrc.h +++ b/include/linux/tfrc.h @@ -37,10 +37,14 @@ struct tfrc_rx_info { * @tfrctx_p: current loss event rate (5.4) * @tfrctx_rto: estimate of RTO, equals 4*RTT (4.3) * @tfrctx_ipi: inter-packet interval (4.6) + * + * Note: X and X_recv are both maintained in units of 64 * bytes/second. This + * enables a finer resolution of sending rates and avoids problems with + * integer arithmetic; u32 is not sufficient as scaling consumes 6 bits. */ struct tfrc_tx_info { - __u32 tfrctx_x; - __u32 tfrctx_x_recv; + __u64 tfrctx_x; + __u64 tfrctx_x_recv; __u32 tfrctx_x_calc; __u32 tfrctx_rtt; __u32 tfrctx_p; |