Re: X much slower in 2.0.24 than in 1.2.13

Nuno Grilo (l38486@alfa.ist.utl.pt)
Wed, 06 Nov 1996 23:39:54 +0000

In message <Pine.LNX.3.91.961106114401.25094A-100000@linux.cs.Helsinki.FI>, Lin
us Torvalds writes:
>
>
>However, the net/sock.h change does two separate things:
> - the TCP sequence number addition for ka9q-based stacks
> - a 16->32 bit counter change
>
>Can you test if the detrimental effect comes from _only_ the short->int
>changes? In that case it seems like the 24 behaviour is just due to
>better counters, and maybe the slowdown is just due to a limit check that
>never triggered due to 16-bit overflows or something like that..
>

After several kernel recompiles here's what I found out:

size field performence
------------------------------------
short bytes_rcv
short rcvbuf good
short sndbuf
-----------------------------------
int bytes_rcv
short rcvbuf good
short sndbuf
-----------------------------------
int bytes_rcv
int rcvbuf good
short sndbuf
-----------------------------------
int bytes_rcv
short rcvbuf BAD
int sndbuf
-----------------------------------

So it appears that the problem is on the sndbuf field