Quoting Ian McDonald:
| > > In short: my suggestion is to keep an experimental patch for this and I would even offer to
| > > keep one up-to-date and online, if in return we can simplify the socket API. Does
| > > this sound like a more convincing argument?
| >
| > Fair enough, I think we should go this way for now, please post here
| > the patch that provides the experimental feature of explicitely
| > setting the packet size, interested people can try and use it and
| > report their findings, later we can get back and possibly merge the
| > patch if it proves useful.
| >
| Basically my patches from a month or two ago would do this with a few
| changes. I'd say merge average patch, I'll update mine to go on top
| (tomorrow??) and allow a mechanism to switch to use it.
To make your work a trifle easier, I have performed and combined the two patches I have sent
to give a reverse patch. The one below works on top of the current tree and basically restores
the state of before the moving-average.
------------------------here is the patch-----------------------------------------------------
[DCCP]: Experimental Patch -- Set packet size `s' via socket options
This patch is for experimentation and research and makes it possible to
explicitly set the CCID 3 packet size `s' via socket options.
This feature overrides the in-kernel automatic tracking of packet sizes in the
CCID 3 module.
To make use of this feature, use e.g.
int psizd = 512; /* your fixed application payload size */
setsockopt(fd, SOL_DCCP, DCCP_SOCKOPT_PACKET_SIZE, &psize, sizeof(psize));
and a corresponding getsockopt() call.
---
include/linux/dccp.h | 4 ++-
net/dccp/ccids/ccid3.c | 54 +++++++++++++++----------------------------------
net/dccp/ccids/ccid3.h | 4 +++
net/dccp/proto.c | 8 +++----
4 files changed, 28 insertions(+), 42 deletions(-)
--- a/net/dccp/ccids/ccid3.c
+++ b/net/dccp/ccids/ccid3.c
@@ -161,24 +161,6 @@ static void ccid3_hc_tx_update_x(struct
ccid3_update_send_time(hctx);
}
-/*
- * Track the mean packet size `s' (cf. RFC 4342, 5.3 and RFC 3448, 4.1)
- * @len: DCCP packet payload size in bytes
- */
-static inline void ccid3_hc_tx_update_s(struct ccid3_hc_tx_sock *hctx, int len)
-{
- if(len == 0)
- ccid3_pr_debug("Packet payload length is 0 - not updating\n");
- else
- hctx->ccid3hctx_s = (hctx->ccid3hctx_s == 0)? len
- : (9 * hctx->ccid3hctx_s + len) / 10;
-
- /* Note: We could do a potential optimisation here - when `s' changes,
- recalculate sending rate and consequently t_ipi, t_delta, and
- t_now. This is however non-standard, and the benefits are not
- clear, so it is currently left out. */
-}
-
static void ccid3_hc_tx_no_feedback_timer(unsigned long data)
{
struct sock *sk = (struct sock *)data;
@@ -317,7 +299,6 @@ static int ccid3_hc_tx_send_packet(struc
ccid3_hc_tx_set_state(sk, TFRC_SSTATE_NO_FBACK);
/* Set initial sending rate to 1 packet per second */
- ccid3_hc_tx_update_s(hctx, skb->len);
hctx->ccid3hctx_x = hctx->ccid3hctx_s;
/* First timeout, according to [RFC 3448, 4.2], is 1 second */
@@ -368,8 +349,6 @@ static void ccid3_hc_tx_packet_sent(stru
dccp_timestamp(sk, &now);
- ccid3_hc_tx_update_s(hctx, len);
-
packet = dccp_tx_hist_head(&hctx->ccid3hctx_hist);
if (unlikely(packet == NULL)) {
DCCP_WARN("packet doesn't exist in history!\n");
@@ -612,9 +591,15 @@ static int ccid3_hc_tx_parse_options(str
static int ccid3_hc_tx_init(struct ccid *ccid, struct sock *sk)
{
+ struct dccp_sock *dp = dccp_sk(sk);
struct ccid3_hc_tx_sock *hctx = ccid_priv(ccid);
- hctx->ccid3hctx_s = 0;
+ if (dp->dccps_packet_size >= TFRC_MIN_PACKET_SIZE &&
+ dp->dccps_packet_size <= TFRC_MAX_PACKET_SIZE)
+ hctx->ccid3hctx_s = dp->dccps_packet_size;
+ else
+ hctx->ccid3hctx_s = TFRC_STD_PACKET_SIZE;
+
hctx->ccid3hctx_state = TFRC_SSTATE_NO_SENT;
INIT_LIST_HEAD(&hctx->ccid3hctx_hist);
@@ -668,15 +653,6 @@ static void ccid3_hc_rx_set_state(struct
hcrx->ccid3hcrx_state = state;
}
-static inline void ccid3_hc_rx_update_s(struct ccid3_hc_rx_sock *hcrx, int len)
-{
- if(len == 0) /* don't update on empty packets (e.g. ACKs) */
- ccid3_pr_debug("Packet payload length is 0 - not updating\n");
- else
- hcrx->ccid3hcrx_s = (hcrx->ccid3hcrx_s == 0)? len
- : (9 * hcrx->ccid3hcrx_s + len) / 10;
-}
-
static void ccid3_hc_rx_send_feedback(struct sock *sk)
{
struct ccid3_hc_rx_sock *hcrx = ccid3_hc_rx_sk(sk);
@@ -953,7 +929,7 @@ static void ccid3_hc_rx_packet_recv(stru
struct dccp_rx_hist_entry *packet;
struct timeval now;
u32 p_prev, rtt_prev, r_sample, t_elapsed;
- int loss, payload_size;
+ int loss;
BUG_ON(hcrx == NULL);
@@ -1008,9 +984,6 @@ static void ccid3_hc_rx_packet_recv(stru
if (DCCP_SKB_CB(skb)->dccpd_type == DCCP_PKT_ACK)
return;
- payload_size = skb->len - dccp_hdr(skb)->dccph_doff * 4;
- ccid3_hc_rx_update_s(hcrx, payload_size);
-
switch (hcrx->ccid3hcrx_state) {
case TFRC_RSTATE_NO_DATA:
ccid3_pr_debug("%s, sk=%p(%s), skb=%p, sending initial "
@@ -1021,7 +994,8 @@ static void ccid3_hc_rx_packet_recv(stru
ccid3_hc_rx_set_state(sk, TFRC_RSTATE_DATA);
return;
case TFRC_RSTATE_DATA:
- hcrx->ccid3hcrx_bytes_recv += payload_size;
+ hcrx->ccid3hcrx_bytes_recv += skb->len -
+ dccp_hdr(skb)->dccph_doff * 4;
if (loss)
break;
@@ -1061,16 +1035,22 @@ static void ccid3_hc_rx_packet_recv(stru
static int ccid3_hc_rx_init(struct ccid *ccid, struct sock *sk)
{
+ struct dccp_sock *dp = dccp_sk(sk);
struct ccid3_hc_rx_sock *hcrx = ccid_priv(ccid);
ccid3_pr_debug("%s, sk=%p\n", dccp_role(sk), sk);
+ if (dp->dccps_packet_size >= TFRC_MIN_PACKET_SIZE &&
+ dp->dccps_packet_size <= TFRC_MAX_PACKET_SIZE)
+ hcrx->ccid3hcrx_s = dp->dccps_packet_size;
+ else
+ hcrx->ccid3hcrx_s = TFRC_STD_PACKET_SIZE;
+
hcrx->ccid3hcrx_state = TFRC_RSTATE_NO_DATA;
INIT_LIST_HEAD(&hcrx->ccid3hcrx_hist);
INIT_LIST_HEAD(&hcrx->ccid3hcrx_li_hist);
dccp_timestamp(sk, &hcrx->ccid3hcrx_tstamp_last_ack);
hcrx->ccid3hcrx_tstamp_last_feedback = hcrx->ccid3hcrx_tstamp_last_ack;
- hcrx->ccid3hcrx_s = 0;
hcrx->ccid3hcrx_rtt = 5000; /* XXX 5ms for now... */
return 0;
}
--- a/include/linux/dccp.h
+++ b/include/linux/dccp.h
@@ -200,7 +200,7 @@ struct dccp_so_feat {
};
/* DCCP socket options */
-#define DCCP_SOCKOPT_PACKET_SIZE 1 /* XXX deprecated, without effect */
+#define DCCP_SOCKOPT_PACKET_SIZE 1
#define DCCP_SOCKOPT_SERVICE 2
#define DCCP_SOCKOPT_CHANGE_L 3
#define DCCP_SOCKOPT_CHANGE_R 4
@@ -460,6 +460,7 @@ struct dccp_ackvec;
* @dccps_service_list - second .. last service code on passive socket
* @dccps_timestamp_time - time of latest TIMESTAMP option
* @dccps_timestamp_echo - latest timestamp received on a TIMESTAMP option
+ * @dccps_packet_size - Set thru setsockopt
* @dccps_l_ack_ratio -
* @dccps_r_ack_ratio -
* @dccps_pcslen - sender partial checksum coverage (via sockopt)
@@ -494,6 +495,7 @@ struct dccp_sock {
struct dccp_service_list *dccps_service_list;
struct timeval dccps_timestamp_time;
__u32 dccps_timestamp_echo;
+ __u32 dccps_packet_size;
__u16 dccps_l_ack_ratio;
__u16 dccps_r_ack_ratio;
__u16 dccps_pcslen;
--- a/net/dccp/ccids/ccid3.h
+++ b/net/dccp/ccids/ccid3.h
@@ -42,6 +42,10 @@
#include <linux/tfrc.h>
#include "../ccid.h"
+#define TFRC_MIN_PACKET_SIZE 16
+#define TFRC_STD_PACKET_SIZE 256
+#define TFRC_MAX_PACKET_SIZE 65535
+
/* Two seconds as per RFC 3448 4.2 */
#define TFRC_INITIAL_TIMEOUT (2 * USEC_PER_SEC)
--- a/net/dccp/proto.c
+++ b/net/dccp/proto.c
@@ -470,8 +470,7 @@ static int do_dccp_setsockopt(struct soc
lock_sock(sk);
switch (optname) {
case DCCP_SOCKOPT_PACKET_SIZE:
- DCCP_WARN("sockopt(PACKET_SIZE) is deprecated: fix your app\n");
- err = -EINVAL;
+ dp->dccps_packet_size = val;
break;
case DCCP_SOCKOPT_CHANGE_L:
if (optlen != sizeof(struct dccp_so_feat))
@@ -582,8 +581,9 @@ static int do_dccp_getsockopt(struct soc
switch (optname) {
case DCCP_SOCKOPT_PACKET_SIZE:
- DCCP_WARN("sockopt(PACKET_SIZE) is deprecated: fix your app\n");
- return -EINVAL;
+ val = dp->dccps_packet_size;
+ len = sizeof(dp->dccps_packet_size);
+ break;
case DCCP_SOCKOPT_SERVICE:
return dccp_getsockopt_service(sk, len,
(__be32 __user *)optval, optlen);
-
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