> -----Original Message-----
> From: Paolo Abeni <[email protected]>
> Sent: Monday, July 14, 2025 3:34 PM
> To: Chia-Yu Chang (Nokia) <[email protected]>;
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> [email protected]; [email protected]; Koen De Schepper (Nokia)
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> [email protected]
> Subject: Re: [PATCH v12 net-next 09/15] tcp: accecn: AccECN needs to know
> delivered bytes
>
>
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>
> On 7/4/25 10:53 AM, [email protected] wrote:
> > diff --git a/net/ipv4/tcp_input.c b/net/ipv4/tcp_input.c index
> > eea790295e54..f7d7649612a2 100644
> > --- a/net/ipv4/tcp_input.c
> > +++ b/net/ipv4/tcp_input.c
> > @@ -1050,6 +1050,7 @@ struct tcp_sacktag_state {
> > u64 last_sackt;
> > u32 reord;
> > u32 sack_delivered;
> > + u32 delivered_bytes;
>
> Explicitly mentioning in the commit message that the above fills a 4 bytes
> hole could be helpful for reviewers.
>
Hi Paolo,
Just want to ask to clarify on "the above fills a 4 bytes hole".
Now I see if I move the delivered_bytes to the end of this struct, the pahole
results of ARM32 bit compilation:
[BEFORE PATCH]
struct tcp_sacktag_state {
u64 first_sackt; /* 0 8 */
u64 last_sackt; /* 8 8 */
u32 reord; /* 16 4 */
u32 sack_delivered; /* 20 4 */
int flag; /* 24 4 */
unsigned int mss_now; /* 28 4 */
struct rate_sample * rate; /* 32 4 */
/* size: 40, cachelines: 1, members: 7 */
/* padding: 4 */
/* last cacheline: 40 bytes */
};
[AFTER PATCH]
struct tcp_sacktag_state {
u64 first_sackt; /* 0 8 */
u64 last_sackt; /* 8 8 */
u32 reord; /* 16 4 */
u32 sack_delivered; /* 20 4 */
int flag; /* 24 4 */
unsigned int mss_now; /* 28 4 */
struct rate_sample * rate; /* 32 4 */
u32 delivered_bytes; /* 36 4 */
/* size: 40, cachelines: 1, members: 8 */
/* last cacheline: 40 bytes */
};
And the 64 bit results are:
[BEFORE PATCH]
struct tcp_sacktag_state {
u64 first_sackt; /* 0 8 */
u64 last_sackt; /* 8 8 */
u32 reord; /* 16 4 */
u32 sack_delivered; /* 20 4 */
int flag; /* 24 4 */
unsigned int mss_now; /* 28 4 */
struct rate_sample * rate; /* 32 8 */
/* size: 40, cachelines: 1, members: 7 */
/* last cacheline: 40 bytes */
};
[AFTER PATCH]
struct tcp_sacktag_state {
u64 first_sackt; /* 0 8 */
u64 last_sackt; /* 8 8 */
u32 reord; /* 16 4 */
u32 sack_delivered; /* 20 4 */
int flag; /* 24 4 */
unsigned int mss_now; /* 28 4 */
struct rate_sample * rate; /* 32 8 */
u32 delivered_bytes; /* 40 4 */
/* size: 48, cachelines: 1, members: 8 */
/* padding: 4 */
/* last cacheline: 48 bytes */
};
I see this patch does not create any extra hole and it can reuse the existing
padding 4 Bytes for ARM32 architecture.
Does it match when you mentioned?
BRs,
Chia-Yu
