* [PATCH mptcp-next 1/2] mptcp: never fetch fwd memory from the subflow
@ 2022-06-16 13:26 Paolo Abeni
2022-06-16 13:26 ` [PATCH mptcp-next 2/2] mptcp: drop SK_RECLAIM_* macros Paolo Abeni
2022-06-17 21:54 ` [PATCH mptcp-next 1/2] mptcp: never fetch fwd memory from the subflow Mat Martineau
0 siblings, 2 replies; 4+ messages in thread
From: Paolo Abeni @ 2022-06-16 13:26 UTC (permalink / raw)
To: mptcp
The memory accounting is broken in such exceptional code
path, and after commit 4890b686f408 ("net: keep sk->sk_forward_alloc
as small as possible") we can't find much help there.
Drop the broken code.
Signed-off-by: Paolo Abeni <pabeni@redhat.com>
---
This is possibly for net, but makes sense only on top of recent
net-next patches, so whatever ;)
---
net/mptcp/protocol.c | 11 +++--------
1 file changed, 3 insertions(+), 8 deletions(-)
diff --git a/net/mptcp/protocol.c b/net/mptcp/protocol.c
index 35e3060233c9..390ac5d95664 100644
--- a/net/mptcp/protocol.c
+++ b/net/mptcp/protocol.c
@@ -328,15 +328,10 @@ static bool mptcp_rmem_schedule(struct sock *sk, struct sock *ssk, int size)
amt = sk_mem_pages(size);
amount = amt << PAGE_SHIFT;
- msk->rmem_fwd_alloc += amount;
- if (!__sk_mem_raise_allocated(sk, size, amt, SK_MEM_RECV)) {
- if (ssk->sk_forward_alloc < amount) {
- msk->rmem_fwd_alloc -= amount;
- return false;
- }
+ if (!__sk_mem_raise_allocated(sk, size, amt, SK_MEM_RECV))
+ return false;
- ssk->sk_forward_alloc -= amount;
- }
+ msk->rmem_fwd_alloc += amount;
return true;
}
--
2.35.3
^ permalink raw reply related [flat|nested] 4+ messages in thread
* [PATCH mptcp-next 2/2] mptcp: drop SK_RECLAIM_* macros
2022-06-16 13:26 [PATCH mptcp-next 1/2] mptcp: never fetch fwd memory from the subflow Paolo Abeni
@ 2022-06-16 13:26 ` Paolo Abeni
2022-06-17 21:54 ` [PATCH mptcp-next 1/2] mptcp: never fetch fwd memory from the subflow Mat Martineau
1 sibling, 0 replies; 4+ messages in thread
From: Paolo Abeni @ 2022-06-16 13:26 UTC (permalink / raw)
To: mptcp
After commit 4890b686f408 ("net: keep sk->sk_forward_alloc as small as
possible"), the MPTCP protocol is the last SK_RECLAIM_CHUNK and
SK_RECLAIM_THRESHOLD users.
Update the MPTCP reclaim schema to match the core/TCP one and drop the
mentioned macros. This additionally clean the MPTCP code a bit.
Signed-off-by: Paolo Abeni <pabeni@redhat.com>
---
net/mptcp/protocol.c | 35 ++---------------------------------
1 file changed, 2 insertions(+), 33 deletions(-)
diff --git a/net/mptcp/protocol.c b/net/mptcp/protocol.c
index 390ac5d95664..bc79afa7e76d 100644
--- a/net/mptcp/protocol.c
+++ b/net/mptcp/protocol.c
@@ -181,8 +181,8 @@ static void mptcp_rmem_uncharge(struct sock *sk, int size)
reclaimable = msk->rmem_fwd_alloc - sk_unused_reserved_mem(sk);
/* see sk_mem_uncharge() for the rationale behind the following schema */
- if (unlikely(reclaimable >= SK_RECLAIM_THRESHOLD))
- __mptcp_rmem_reclaim(sk, SK_RECLAIM_CHUNK);
+ if (unlikely(reclaimable >= PAGE_SIZE))
+ __mptcp_rmem_reclaim(sk, reclaimable);
}
static void mptcp_rfree(struct sk_buff *skb)
@@ -961,25 +961,6 @@ static bool mptcp_frag_can_collapse_to(const struct mptcp_sock *msk,
df->data_seq + df->data_len == msk->write_seq;
}
-static void __mptcp_mem_reclaim_partial(struct sock *sk)
-{
- int reclaimable = mptcp_sk(sk)->rmem_fwd_alloc - sk_unused_reserved_mem(sk);
-
- lockdep_assert_held_once(&sk->sk_lock.slock);
-
- if (reclaimable > (int)PAGE_SIZE)
- __mptcp_rmem_reclaim(sk, reclaimable - 1);
-
- sk_mem_reclaim(sk);
-}
-
-static void mptcp_mem_reclaim_partial(struct sock *sk)
-{
- mptcp_data_lock(sk);
- __mptcp_mem_reclaim_partial(sk);
- mptcp_data_unlock(sk);
-}
-
static void dfrag_uncharge(struct sock *sk, int len)
{
sk_mem_uncharge(sk, len);
@@ -999,7 +980,6 @@ static void __mptcp_clean_una(struct sock *sk)
{
struct mptcp_sock *msk = mptcp_sk(sk);
struct mptcp_data_frag *dtmp, *dfrag;
- bool cleaned = false;
u64 snd_una;
/* on fallback we just need to ignore snd_una, as this is really
@@ -1022,7 +1002,6 @@ static void __mptcp_clean_una(struct sock *sk)
}
dfrag_clear(sk, dfrag);
- cleaned = true;
}
dfrag = mptcp_rtx_head(sk);
@@ -1044,7 +1023,6 @@ static void __mptcp_clean_una(struct sock *sk)
dfrag->already_sent -= delta;
dfrag_uncharge(sk, delta);
- cleaned = true;
}
/* all retransmitted data acked, recovery completed */
@@ -1052,9 +1030,6 @@ static void __mptcp_clean_una(struct sock *sk)
msk->recovery = false;
out:
- if (cleaned && tcp_under_memory_pressure(sk))
- __mptcp_mem_reclaim_partial(sk);
-
if (snd_una == READ_ONCE(msk->snd_nxt) &&
snd_una == READ_ONCE(msk->write_seq)) {
if (mptcp_timer_pending(sk) && !mptcp_data_fin_enabled(msk))
@@ -1206,12 +1181,6 @@ static struct sk_buff *mptcp_alloc_tx_skb(struct sock *sk, struct sock *ssk, boo
{
gfp_t gfp = data_lock_held ? GFP_ATOMIC : sk->sk_allocation;
- if (unlikely(tcp_under_memory_pressure(sk))) {
- if (data_lock_held)
- __mptcp_mem_reclaim_partial(sk);
- else
- mptcp_mem_reclaim_partial(sk);
- }
return __mptcp_alloc_tx_skb(sk, ssk, gfp);
}
--
2.35.3
^ permalink raw reply related [flat|nested] 4+ messages in thread
* Re: [PATCH mptcp-next 1/2] mptcp: never fetch fwd memory from the subflow
2022-06-16 13:26 [PATCH mptcp-next 1/2] mptcp: never fetch fwd memory from the subflow Paolo Abeni
2022-06-16 13:26 ` [PATCH mptcp-next 2/2] mptcp: drop SK_RECLAIM_* macros Paolo Abeni
@ 2022-06-17 21:54 ` Mat Martineau
2022-06-20 9:02 ` Paolo Abeni
1 sibling, 1 reply; 4+ messages in thread
From: Mat Martineau @ 2022-06-17 21:54 UTC (permalink / raw)
To: Paolo Abeni; +Cc: mptcp
On Thu, 16 Jun 2022, Paolo Abeni wrote:
> The memory accounting is broken in such exceptional code
> path, and after commit 4890b686f408 ("net: keep sk->sk_forward_alloc
> as small as possible") we can't find much help there.
>
> Drop the broken code.
>
> Signed-off-by: Paolo Abeni <pabeni@redhat.com>
> ---
> This is possibly for net, but makes sense only on top of recent
> net-next patches, so whatever ;)
Let's go with net-next.
> ---
> net/mptcp/protocol.c | 11 +++--------
> 1 file changed, 3 insertions(+), 8 deletions(-)
>
> diff --git a/net/mptcp/protocol.c b/net/mptcp/protocol.c
> index 35e3060233c9..390ac5d95664 100644
> --- a/net/mptcp/protocol.c
> +++ b/net/mptcp/protocol.c
> @@ -328,15 +328,10 @@ static bool mptcp_rmem_schedule(struct sock *sk, struct sock *ssk, int size)
>
> amt = sk_mem_pages(size);
> amount = amt << PAGE_SHIFT;
> - msk->rmem_fwd_alloc += amount;
> - if (!__sk_mem_raise_allocated(sk, size, amt, SK_MEM_RECV)) {
> - if (ssk->sk_forward_alloc < amount) {
> - msk->rmem_fwd_alloc -= amount;
> - return false;
> - }
> + if (!__sk_mem_raise_allocated(sk, size, amt, SK_MEM_RECV))
> + return false;
Like Eric did in 7c80b038d23e, does it makes sense to try to raise the
allocation only by the amount of incremental memory requested (size -
msk->rmem_forward_alloc) rather than the full amount from the 'size' arg?
>
> - ssk->sk_forward_alloc -= amount;
> - }
> + msk->rmem_fwd_alloc += amount;
> return true;
> }
--
Mat Martineau
Intel
^ permalink raw reply [flat|nested] 4+ messages in thread
* Re: [PATCH mptcp-next 1/2] mptcp: never fetch fwd memory from the subflow
2022-06-17 21:54 ` [PATCH mptcp-next 1/2] mptcp: never fetch fwd memory from the subflow Mat Martineau
@ 2022-06-20 9:02 ` Paolo Abeni
0 siblings, 0 replies; 4+ messages in thread
From: Paolo Abeni @ 2022-06-20 9:02 UTC (permalink / raw)
To: Mat Martineau; +Cc: mptcp
On Fri, 2022-06-17 at 14:54 -0700, Mat Martineau wrote:
> On Thu, 16 Jun 2022, Paolo Abeni wrote:
>
> > The memory accounting is broken in such exceptional code
> > path, and after commit 4890b686f408 ("net: keep sk->sk_forward_alloc
> > as small as possible") we can't find much help there.
> >
> > Drop the broken code.
> >
> > Signed-off-by: Paolo Abeni <pabeni@redhat.com>
> > ---
> > This is possibly for net, but makes sense only on top of recent
> > net-next patches, so whatever ;)
>
> Let's go with net-next.
>
> > ---
> > net/mptcp/protocol.c | 11 +++--------
> > 1 file changed, 3 insertions(+), 8 deletions(-)
> >
> > diff --git a/net/mptcp/protocol.c b/net/mptcp/protocol.c
> > index 35e3060233c9..390ac5d95664 100644
> > --- a/net/mptcp/protocol.c
> > +++ b/net/mptcp/protocol.c
> > @@ -328,15 +328,10 @@ static bool mptcp_rmem_schedule(struct sock *sk, struct sock *ssk, int size)
> >
> > amt = sk_mem_pages(size);
> > amount = amt << PAGE_SHIFT;
> > - msk->rmem_fwd_alloc += amount;
> > - if (!__sk_mem_raise_allocated(sk, size, amt, SK_MEM_RECV)) {
> > - if (ssk->sk_forward_alloc < amount) {
> > - msk->rmem_fwd_alloc -= amount;
> > - return false;
> > - }
> > + if (!__sk_mem_raise_allocated(sk, size, amt, SK_MEM_RECV))
> > + return false;
>
> Like Eric did in 7c80b038d23e, does it makes sense to try to raise the
> allocation only by the amount of incremental memory requested (size -
> msk->rmem_forward_alloc) rather than the full amount from the 'size' arg?
Ok, but let's put such change on a different commit. Upstream just
reported a huge regression in SCTP due to the above change, and I
haven't benchmarked MPTCP yet. Keeping the change separate we can
revert/fix/backport fix more easily.
Cheers,
Paolo
^ permalink raw reply [flat|nested] 4+ messages in thread
end of thread, other threads:[~2022-06-20 9:02 UTC | newest]
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