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authorGerrit Renker <gerrit@erg.abdn.ac.uk>2006-12-10 05:02:12 +0300
committerDavid S. Miller <davem@sunset.davemloft.net>2006-12-12 01:34:42 +0300
commit1a21e49a8d60f588c1276f765198b14d5688a778 (patch)
tree4b8770be71047437f30da694649719948977b189 /include/linux/tfrc.h
parent179ebc9f92da88e15ea86d7d27308c92712d8ee9 (diff)
downloadlinux-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.h8
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;