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  1. 04 10月, 2005 3 次提交
    • H
      [IPV4]: Fix "Proxy ARP seems broken" · 444fc8fc
      由 Herbert Xu 提交于 
      Meelis Roos <mroos@linux.ee> wrote:
> RK> My firewall setup relies on proxyarp working.  However, with 2.6.14-rc3,
> RK> it appears to be completely broken.  The firewall is 212.18.232.186,
> 
> Same here with some kernel between 14-rc2 and 14-rc3 - no reposnse to
> ARP on a proxyarp gateway. Sorry, no exact revison and no more debugging
> yet since it'a a production gateway.

The breakage is caused by the change to use the CB area for flagging
whether a packet has been queued due to proxy_delay.  This area gets
cleared every time arp_rcv gets called.  Unfortunately packets delayed
due to proxy_delay also go through arp_rcv when they are reprocessed.

In fact, I can't think of a reason why delayed proxy packets should go
through netfilter again at all.  So the easiest solution is to bypass
that and go straight to arp_process.

This is essentially what would've happened before netfilter support
was added to ARP.

Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au> 
Signed-off-by: NDavid S. Miller <davem@davemloft.net>
      444fc8fc
    • E
      [INET]: speedup inet (tcp/dccp) lookups · 81c3d547
      由 Eric Dumazet 提交于 
      Arnaldo and I agreed it could be applied now, because I have other
pending patches depending on this one (Thank you Arnaldo)

(The other important patch moves skc_refcnt in a separate cache line,
so that the SMP/NUMA performance doesnt suffer from cache line ping pongs)

1) First some performance data :
--------------------------------

tcp_v4_rcv() wastes a *lot* of time in __inet_lookup_established()

The most time critical code is :

sk_for_each(sk, node, &head->chain) {
     if (INET_MATCH(sk, acookie, saddr, daddr, ports, dif))
         goto hit; /* You sunk my battleship! */
}

The sk_for_each() does use prefetch() hints but only the begining of
"struct sock" is prefetched.

As INET_MATCH first comparison uses inet_sk(__sk)->daddr, wich is far
away from the begining of "struct sock", it has to bring into CPU
cache cold cache line. Each iteration has to use at least 2 cache
lines.

This can be problematic if some chains are very long.

2) The goal
-----------

The idea I had is to change things so that INET_MATCH() may return
FALSE in 99% of cases only using the data already in the CPU cache,
using one cache line per iteration.

3) Description of the patch
---------------------------

Adds a new 'unsigned int skc_hash' field in 'struct sock_common',
filling a 32 bits hole on 64 bits platform.

struct sock_common {
	unsigned short		skc_family;
	volatile unsigned char	skc_state;
	unsigned char		skc_reuse;
	int			skc_bound_dev_if;
	struct hlist_node	skc_node;
	struct hlist_node	skc_bind_node;
	atomic_t		skc_refcnt;
+	unsigned int		skc_hash;
	struct proto		*skc_prot;
};

Store in this 32 bits field the full hash, not masked by (ehash_size -
1) Using this full hash as the first comparison done in INET_MATCH
permits us immediatly skip the element without touching a second cache
line in case of a miss.

Suppress the sk_hashent/tw_hashent fields since skc_hash (aliased to
sk_hash and tw_hash) already contains the slot number if we mask with
(ehash_size - 1)

File include/net/inet_hashtables.h

64 bits platforms :
#define INET_MATCH(__sk, __hash, __cookie, __saddr, __daddr, __ports, __dif)\
     (((__sk)->sk_hash == (__hash))
     ((*((__u64 *)&(inet_sk(__sk)->daddr)))== (__cookie))   &&  \
     ((*((__u32 *)&(inet_sk(__sk)->dport))) == (__ports))   &&  \
     (!((__sk)->sk_bound_dev_if) || ((__sk)->sk_bound_dev_if == (__dif))))

32bits platforms:
#define TCP_IPV4_MATCH(__sk, __hash, __cookie, __saddr, __daddr, __ports, __dif)\
     (((__sk)->sk_hash == (__hash))                 &&  \
     (inet_sk(__sk)->daddr          == (__saddr))   &&  \
     (inet_sk(__sk)->rcv_saddr      == (__daddr))   &&  \
     (!((__sk)->sk_bound_dev_if) || ((__sk)->sk_bound_dev_if == (__dif))))


- Adds a prefetch(head->chain.first) in 
__inet_lookup_established()/__tcp_v4_check_established() and 
__inet6_lookup_established()/__tcp_v6_check_established() and 
__dccp_v4_check_established() to bring into cache the first element of the 
list, before the {read|write}_lock(&head->lock);
Signed-off-by: NEric Dumazet <dada1@cosmosbay.com>
Acked-by: NArnaldo Carvalho de Melo <acme@ghostprotocols.net>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>
      81c3d547
    • H
      [NET]: Fix packet timestamping. · 325ed823
      由 Herbert Xu 提交于 
      I've found the problem in general.  It affects any 64-bit
architecture.  The problem occurs when you change the system time.

Suppose that when you boot your system clock is forward by a day.
This gets recorded down in skb_tv_base.  You then wind the clock back
by a day.  From that point onwards the offset will be negative which
essentially overflows the 32-bit variables they're stored in.

In fact, why don't we just store the real time stamp in those 32-bit
variables? After all, we're not going to overflow for quite a while
yet.

When we do overflow, we'll need a better solution of course.
Signed-off-by: NHerbert Xu <herbert@gondor.apana.org.au>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>
      325ed823
  3. 30 9月, 2005 2 次提交
    • A
      [TCP]: Don't over-clamp window in tcp_clamp_window() · 09e9ec87
      由 Alexey Kuznetsov 提交于 
      From: Alexey Kuznetsov <kuznet@ms2.inr.ac.ru>

Handle better the case where the sender sends full sized
frames initially, then moves to a mode where it trickles
out small amounts of data at a time.

This known problem is even mentioned in the comments
above tcp_grow_window() in tcp_input.c, specifically:

...
 * The scheme does not work when sender sends good segments opening
 * window and then starts to feed us spagetti. But it should work
 * in common situations. Otherwise, we have to rely on queue collapsing.
...

When the sender gives full sized frames, the "struct sk_buff" overhead
from each packet is small.  So we'll advertize a larger window.
If the sender moves to a mode where small segments are sent, this
ratio becomes tilted to the other extreme and we start overrunning
the socket buffer space.

tcp_clamp_window() tries to address this, but it's clamping of
tp->window_clamp is a wee bit too aggressive for this particular case.

Fix confirmed by Ion Badulescu.
Signed-off-by: NDavid S. Miller <davem@davemloft.net>
      09e9ec87
    • D
      [TCP]: Revert 6b251858 · 01ff367e
      由 David S. Miller 提交于 
      But retain the comment fix.

Alexey Kuznetsov has explained the situation as follows:

--------------------

I think the fix is incorrect. Look, the RFC function init_cwnd(mss) is
not continuous: f.e. for mss=1095 it needs initial window 1095*4, but
for mss=1096 it is 1096*3. We do not know exactly what mss sender used
for calculations. If we advertised 1096 (and calculate initial window
3*1096), the sender could limit it to some value < 1096 and then it
will need window his_mss*4 > 3*1096 to send initial burst.

See?

So, the honest function for inital rcv_wnd derived from
tcp_init_cwnd() is:

	init_rcv_wnd(mss)=
	  min { init_cwnd(mss1)*mss1 for mss1 <= mss }

It is something sort of:

	if (mss < 1096)
		return mss*4;
	if (mss < 1096*2)
		return 1096*4;
	return mss*2;

(I just scrablled a graph of piece of paper, it is difficult to see or
to explain without this)

I selected it differently giving more window than it is strictly
required.  Initial receive window must be large enough to allow sender
following to the rfc (or just setting initial cwnd to 2) to send
initial burst.  But besides that it is arbitrary, so I decided to give
slack space of one segment.

Actually, the logic was:

If mss is low/normal (<=ethernet), set window to receive more than
initial burst allowed by rfc under the worst conditions
i.e. mss*4. This gives slack space of 1 segment for ethernet frames.

For msses slighlty more than ethernet frame, take 3. Try to give slack
space of 1 frame again.

If mss is huge, force 2*mss. No slack space.

Value 1460*3 is really confusing. Minimal one is 1096*2, but besides
that it is an arbitrary value. It was meant to be ~4096. 1460*3 is
just the magic number from RFC, 1460*3 = 1095*4 is the magic :-), so
that I guess hands typed this themselves.

--------------------
Signed-off-by: NDavid S. Miller <davem@davemloft.net>
      01ff367e
  5. 29 9月, 2005 1 次提交
  7. 27 9月, 2005 1 次提交
    • H
      [NETFILTER]: Fix invalid module autoloading by splitting iptable_nat · 188bab3a
      由 Harald Welte 提交于 
      When you've enabled conntrack and NAT as a module (standard case in all
distributions), and you've also enabled the new conntrack netlink
interface, loading ip_conntrack_netlink.ko will auto-load iptable_nat.ko.
This causes a huge performance penalty, since for every packet you iterate
the nat code, even if you don't want it.

This patch splits iptable_nat.ko into the NAT core (ip_nat.ko) and the
iptables frontend (iptable_nat.ko).  Threfore, ip_conntrack_netlink.ko will
only pull ip_nat.ko, but not the frontend.  ip_nat.ko will "only" allocate
some resources, but not affect runtime performance.

This separation is also a nice step in anticipation of new packet filters
(nf-hipac, ipset, pkttables) being able to use the NAT core.
Signed-off-by: NHarald Welte <laforge@netfilter.org>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>
      188bab3a
  9. 25 9月, 2005 2 次提交
  11. 23 9月, 2005 4 次提交
  13. 21 9月, 2005 2 次提交
  15. 20 9月, 2005 7 次提交
  17. 18 9月, 2005 1 次提交
  19. 17 9月, 2005 4 次提交
  21. 15 9月, 2005 4 次提交
  23. 14 9月, 2005 4 次提交
  25. 13 9月, 2005 1 次提交
  27. 11 9月, 2005 1 次提交
  29. 10 9月, 2005 3 次提交