From: Paolo Abeni <pabeni@redhat.com>
To: mptcp@lists.linux.dev
Cc: fwestpha@redhat.com
Subject: [PATCH mptcp-next 2/7] mptcp: less aggressive retransmission stragegy
Date: Mon, 28 Jun 2021 17:54:06 +0200 [thread overview]
Message-ID: <61a90dcbb54b9477b4ef3539e35fa7499c0b2c83.1624895054.git.pabeni@redhat.com> (raw)
In-Reply-To: <cover.1624895054.git.pabeni@redhat.com>
The current mptcp re-inject strategy is very aggressive,
we have mptcp-level retransmissions even on single subflow
connection, if the link in-use is lossy.
Let's be a little more conservative: we do retransmission
only if at least a subflow has write and rtx queue empty.
Additionally use the backup subflows only if the active
subflows are stale - no progresses in at least an rtx period.
Closes: https://github.com/multipath-tcp/mptcp_net-next/issues/207
Signed-off-by: Paolo Abeni <pabeni@redhat.com>
---
net/mptcp/pm.c | 17 +++++++++++++++++
net/mptcp/protocol.c | 22 ++++++++++++++--------
net/mptcp/protocol.h | 5 ++++-
3 files changed, 35 insertions(+), 9 deletions(-)
diff --git a/net/mptcp/pm.c b/net/mptcp/pm.c
index 639271e09604..9ff17c5205ce 100644
--- a/net/mptcp/pm.c
+++ b/net/mptcp/pm.c
@@ -308,6 +308,23 @@ int mptcp_pm_get_local_id(struct mptcp_sock *msk, struct sock_common *skc)
return mptcp_pm_nl_get_local_id(msk, skc);
}
+void mptcp_pm_subflow_chk_stale(const struct mptcp_sock *msk, struct sock *ssk)
+{
+ struct mptcp_subflow_context *subflow = mptcp_subflow_ctx(ssk);
+ u32 rcv_tstamp = READ_ONCE(tcp_sk(ssk)->rcv_tstamp);
+
+ /* keep track of rtx periods with no progress */
+ if (!subflow->stale_count) {
+ subflow->stale_rcv_tstamp = rcv_tstamp;
+ subflow->stale_count++;
+ } else if (subflow->stale_rcv_tstamp == rcv_tstamp) {
+ if (subflow->stale_count < U8_MAX)
+ subflow->stale_count++;
+ } else {
+ subflow->stale_count = 0;
+ }
+}
+
void mptcp_pm_data_init(struct mptcp_sock *msk)
{
msk->pm.add_addr_signaled = 0;
diff --git a/net/mptcp/protocol.c b/net/mptcp/protocol.c
index 291f0e2279a8..51f608831fae 100644
--- a/net/mptcp/protocol.c
+++ b/net/mptcp/protocol.c
@@ -2088,8 +2088,9 @@ static void mptcp_timeout_timer(struct timer_list *t)
*/
static struct sock *mptcp_subflow_get_retrans(const struct mptcp_sock *msk)
{
+ struct sock *backup = NULL, *pick = NULL;
struct mptcp_subflow_context *subflow;
- struct sock *backup = NULL;
+ int min_stale_count = INT_MAX;
sock_owned_by_me((const struct sock *)msk);
@@ -2102,11 +2103,11 @@ static struct sock *mptcp_subflow_get_retrans(const struct mptcp_sock *msk)
if (!mptcp_subflow_active(subflow))
continue;
- /* still data outstanding at TCP level? Don't retransmit. */
- if (!tcp_write_queue_empty(ssk)) {
- if (inet_csk(ssk)->icsk_ca_state >= TCP_CA_Loss)
- continue;
- return NULL;
+ /* still data outstanding at TCP level? skip this */
+ if (!tcp_rtx_and_write_queues_empty(ssk)) {
+ mptcp_pm_subflow_chk_stale(msk, ssk);
+ min_stale_count = min_t(int, min_stale_count, subflow->stale_count);
+ continue;
}
if (subflow->backup) {
@@ -2115,10 +2116,15 @@ static struct sock *mptcp_subflow_get_retrans(const struct mptcp_sock *msk)
continue;
}
- return ssk;
+ if (!pick)
+ pick = ssk;
}
- return backup;
+ if (pick)
+ return pick;
+
+ /* use backup only if there are no progresses anywhere */
+ return min_stale_count > 1 ? backup : NULL;
}
static void mptcp_dispose_initial_subflow(struct mptcp_sock *msk)
diff --git a/net/mptcp/protocol.h b/net/mptcp/protocol.h
index 0f0c026c5f8b..6a3cbdb597e2 100644
--- a/net/mptcp/protocol.h
+++ b/net/mptcp/protocol.h
@@ -439,11 +439,13 @@ struct mptcp_subflow_context {
u8 reset_seen:1;
u8 reset_transient:1;
u8 reset_reason:4;
+ u8 stale_count;
long delegated_status;
struct list_head delegated_node; /* link into delegated_action, protected by local BH */
- u32 setsockopt_seq;
+ u32 setsockopt_seq;
+ u32 stale_rcv_tstamp;
struct sock *tcp_sock; /* tcp sk backpointer */
struct sock *conn; /* parent mptcp_sock */
@@ -690,6 +692,7 @@ void mptcp_crypto_hmac_sha(u64 key1, u64 key2, u8 *msg, int len, void *hmac);
void __init mptcp_pm_init(void);
void mptcp_pm_data_init(struct mptcp_sock *msk);
+void mptcp_pm_subflow_chk_stale(const struct mptcp_sock *msk, struct sock *ssk);
void mptcp_pm_new_connection(struct mptcp_sock *msk, const struct sock *ssk, int server_side);
void mptcp_pm_fully_established(struct mptcp_sock *msk, const struct sock *ssk, gfp_t gfp);
bool mptcp_pm_allow_new_subflow(struct mptcp_sock *msk);
--
2.26.3
next prev parent reply other threads:[~2021-06-28 16:07 UTC|newest]
Thread overview: 12+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-06-28 15:54 [PATCH mptcp-next 0/7] mptcp: refactor active backup Paolo Abeni
2021-06-28 15:54 ` [PATCH mptcp-next 1/7] mptcp: more accurate timeout Paolo Abeni
2021-06-28 15:54 ` Paolo Abeni [this message]
2021-06-28 15:54 ` [PATCH mptcp-next 3/7] mptcp: handle pending data on closed subflow Paolo Abeni
2021-07-09 0:44 ` Mat Martineau
2021-06-28 15:54 ` [PATCH mptcp-next 4/7] mptcp: faster active backup recovery Paolo Abeni
2021-06-28 15:54 ` [PATCH mptcp-next 5/7] mptcp: add mibs for stale subflows processing Paolo Abeni
2021-06-28 15:54 ` [PATCH mptcp-next 6/7] mptcp: backup flag from incoming MPJ ack option Paolo Abeni
2021-06-28 15:54 ` [PATCH mptcp-next 7/7] selftests: mptcp: add testcase for active-back Paolo Abeni
2021-07-09 0:51 ` Mat Martineau
2021-07-09 7:04 ` Paolo Abeni
2021-07-09 1:13 ` [PATCH mptcp-next 0/7] mptcp: refactor active backup Mat Martineau
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=61a90dcbb54b9477b4ef3539e35fa7499c0b2c83.1624895054.git.pabeni@redhat.com \
--to=pabeni@redhat.com \
--cc=fwestpha@redhat.com \
--cc=mptcp@lists.linux.dev \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).