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| author | Gerrit Renker <gerrit@erg.abdn.ac.uk> | 2008-09-04 07:30:19 +0200 |
|---|---|---|
| committer | Gerrit Renker <gerrit@erg.abdn.ac.uk> | 2008-09-04 07:45:34 +0200 |
| commit | 535c55df136ad2783d444e54d518a8fae8bdbf79 (patch) | |
| tree | 8f7b18bc7b82270e78061c4c22bf722534b743a1 /net/dccp/ccids/ccid3.c | |
| parent | dccp: Add packet type information to CCID-specific option parsing (diff) | |
| download | linux-535c55df136ad2783d444e54d518a8fae8bdbf79.tar.xz linux-535c55df136ad2783d444e54d518a8fae8bdbf79.zip | |
dccp tfrc/ccid-3: Computing Loss Rate from Loss Event Rate
This adds a function to take care of the following cases occurring in the
computation of the Loss Rate p:
* 1/(2^32-1) is mapped into 0% as per RFC 4342, 8.5;
* 1/0 is mapped into the maximum of 100%;
* we want to avoid that p = 1/x is rounded down to 0 when x is very large,
since this means accidentally re-entering slow-start (indicated by p==0).
In the last case, the minimum-resolution value of p is returned.
Furthermore, a bug in ccid3_hc_rx_getsockopt is fixed (1/0 was mapped into ~0U),
which now allows to consistently print the scaled p-values as
printf("Loss Event Rate = %u.%04u %%\n", rx_info.tfrcrx_p / 10000,
rx_info.tfrcrx_p % 10000);
Signed-off-by: Gerrit Renker <gerrit@erg.abdn.ac.uk>
Diffstat (limited to 'net/dccp/ccids/ccid3.c')
| -rw-r--r-- | net/dccp/ccids/ccid3.c | 9 |
1 files changed, 4 insertions, 5 deletions
diff --git a/net/dccp/ccids/ccid3.c b/net/dccp/ccids/ccid3.c index 4c422fb2189f..206204551f4d 100644 --- a/net/dccp/ccids/ccid3.c +++ b/net/dccp/ccids/ccid3.c @@ -410,10 +410,10 @@ static void ccid3_hc_tx_packet_recv(struct sock *sk, struct sk_buff *skb) /* Update loss event rate (which is scaled by 1e6) */ pinv = opt_recv->ccid3or_loss_event_rate; - if (pinv == ~0U || pinv == 0) /* see RFC 4342, 8.5 */ + if (pinv == 0) hctx->p = 0; - else /* can not exceed 100% */ - hctx->p = scaled_div(1, pinv); + else + hctx->p = tfrc_invert_loss_event_rate(pinv); /* * Update allowed sending rate X as per draft rfc3448bis-00, 4.2/3 @@ -854,8 +854,7 @@ static int ccid3_hc_rx_getsockopt(struct sock *sk, const int optname, int len, return -EINVAL; rx_info.tfrcrx_x_recv = hcrx->x_recv; rx_info.tfrcrx_rtt = hcrx->rtt; - rx_info.tfrcrx_p = hcrx->p_inverse == 0 ? ~0U : - scaled_div(1, hcrx->p_inverse); + rx_info.tfrcrx_p = tfrc_invert_loss_event_rate(hcrx->p_inverse); len = sizeof(rx_info); val = &rx_info; break; |