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Date: Sat, 26 Aug 2017 11:56:05 -0700
From: Florian Fainelli <f.fainelli@...il.com>
To: Eric Dumazet <eric.dumazet@...il.com>,
David Miller <davem@...emloft.net>
Cc: netdev@...r.kernel.org, pabeni@...hat.com, willemb@...gle.com
Subject: Re: UDP sockets oddities
On 08/26/2017 05:47 AM, Eric Dumazet wrote:
> On Fri, 2017-08-25 at 21:19 -0700, David Miller wrote:
>
>> Agreed, but the ARP resolution queue really needs to scale it's backlog
>> to the physical technology it is attached to.
> Yes, last time (in 2011) we increased the old limit of 3 packets :/
>
> We probably should match sysctl_wmem_max so that a single socket
> provider would hit its sk_sndbuf limit
Before:
/proc/sys/net/ipv4/neigh/eth0/unres_qlen:34
/proc/sys/net/ipv4/neigh/eth0/unres_qlen_bytes:65536
/proc/sys/net/ipv4/neigh/gphy/unres_qlen:34
/proc/sys/net/ipv4/neigh/gphy/unres_qlen_bytes:65536
After:
/proc/sys/net/ipv4/neigh/eth0/unres_qlen:106
/proc/sys/net/ipv4/neigh/eth0/unres_qlen_bytes:229376
/proc/sys/net/ipv4/neigh/gphy/unres_qlen:106
/proc/sys/net/ipv4/neigh/gphy/unres_qlen_bytes:229376
and this does help a lot with the test case reported over an hour, only
2 packets lost:
# perf record -a -g -e skb:kfree_skb iperf -c 192.168.1.23 -b 900M -t
3600 -u
------------------------------------------------------------
Client connecting to 192.168.1.23, UDP port 5001
Sending 1470 byte datagrams, IPG target: 13.07 us (kalman adjust)
UDP buffer size: 224 KByte (default)
------------------------------------------------------------
[ 4] local 192.168.1.66 port 48209 connected with 192.168.1.23 port 5001
write failed: Invalid argument
[ ID] Interval Transfer Bandwidth
[ 4] 0.0-404.9 sec 4.51 GBytes 95.7 Mbits/sec
[ 4] Sent 3294727 datagrams
[ 4] Server Report:
[ 4] 0.0-405.1 sec 4.51 GBytes 95.6 Mbits/sec 14.979 ms
2/3294728 (6.1e-05%)
Thanks Eric!
>
> Something like :
>
> diff --git a/Documentation/networking/ip-sysctl.txt b/Documentation/networking/ip-sysctl.txt
> index 6b0bc0f715346a097a6df46e2ba2771359abcd23..7777dceb78107c0019fb39d5b69be1959005b78e 100644
> --- a/Documentation/networking/ip-sysctl.txt
> +++ b/Documentation/networking/ip-sysctl.txt
> @@ -109,7 +109,8 @@ neigh/default/unres_qlen_bytes - INTEGER
> queued for each unresolved address by other network layers.
> (added in linux 3.3)
> Setting negative value is meaningless and will return error.
> - Default: 65536 Bytes(64KB)
> + Default: SK_WMEM_MAX, enough to store 256 packets of medium size
> + (less than 256 bytes per packet)
>
> neigh/default/unres_qlen - INTEGER
> The maximum number of packets which may be queued for each
> diff --git a/include/net/sock.h b/include/net/sock.h
> index 1c2912d433e81b10f3fdc87bcfcbb091570edc03..03a362568357acc7278a318423dd3873103f90ca 100644
> --- a/include/net/sock.h
> +++ b/include/net/sock.h
> @@ -2368,6 +2368,16 @@ bool sk_net_capable(const struct sock *sk, int cap);
>
> void sk_get_meminfo(const struct sock *sk, u32 *meminfo);
>
> +/* Take into consideration the size of the struct sk_buff overhead in the
> + * determination of these values, since that is non-constant across
> + * platforms. This makes socket queueing behavior and performance
> + * not depend upon such differences.
> + */
> +#define _SK_MEM_PACKETS 256
> +#define _SK_MEM_OVERHEAD SKB_TRUESIZE(256)
> +#define SK_WMEM_MAX (_SK_MEM_OVERHEAD * _SK_MEM_PACKETS)
> +#define SK_RMEM_MAX (_SK_MEM_OVERHEAD * _SK_MEM_PACKETS)
> +
> extern __u32 sysctl_wmem_max;
> extern __u32 sysctl_rmem_max;
>
> diff --git a/net/core/sock.c b/net/core/sock.c
> index dfdd14cac775e9bfcee0085ee32ffcd0ab28b67b..9b7b6bbb2a23e7652a1f34a305f29d49de00bc8c 100644
> --- a/net/core/sock.c
> +++ b/net/core/sock.c
> @@ -307,16 +307,6 @@ static struct lock_class_key af_wlock_keys[AF_MAX];
> static struct lock_class_key af_elock_keys[AF_MAX];
> static struct lock_class_key af_kern_callback_keys[AF_MAX];
>
> -/* Take into consideration the size of the struct sk_buff overhead in the
> - * determination of these values, since that is non-constant across
> - * platforms. This makes socket queueing behavior and performance
> - * not depend upon such differences.
> - */
> -#define _SK_MEM_PACKETS 256
> -#define _SK_MEM_OVERHEAD SKB_TRUESIZE(256)
> -#define SK_WMEM_MAX (_SK_MEM_OVERHEAD * _SK_MEM_PACKETS)
> -#define SK_RMEM_MAX (_SK_MEM_OVERHEAD * _SK_MEM_PACKETS)
> -
> /* Run time adjustable parameters. */
> __u32 sysctl_wmem_max __read_mostly = SK_WMEM_MAX;
> EXPORT_SYMBOL(sysctl_wmem_max);
> diff --git a/net/decnet/dn_neigh.c b/net/decnet/dn_neigh.c
> index 21dedf6fd0f76dec22b2b3685beb89cfefea7ded..22bf0b95d6edc3c27ef3a99d27cb70a1551e3e0e 100644
> --- a/net/decnet/dn_neigh.c
> +++ b/net/decnet/dn_neigh.c
> @@ -94,7 +94,7 @@ struct neigh_table dn_neigh_table = {
> [NEIGH_VAR_BASE_REACHABLE_TIME] = 30 * HZ,
> [NEIGH_VAR_DELAY_PROBE_TIME] = 5 * HZ,
> [NEIGH_VAR_GC_STALETIME] = 60 * HZ,
> - [NEIGH_VAR_QUEUE_LEN_BYTES] = 64*1024,
> + [NEIGH_VAR_QUEUE_LEN_BYTES] = SK_WMEM_MAX,
> [NEIGH_VAR_PROXY_QLEN] = 0,
> [NEIGH_VAR_ANYCAST_DELAY] = 0,
> [NEIGH_VAR_PROXY_DELAY] = 0,
> diff --git a/net/ipv4/arp.c b/net/ipv4/arp.c
> index 8b52179ddc6e54eabf6d3c2ed0132083228680bb..7c45b8896709815c5dde5972fd57cb5c3bcb2648 100644
> --- a/net/ipv4/arp.c
> +++ b/net/ipv4/arp.c
> @@ -171,7 +171,7 @@ struct neigh_table arp_tbl = {
> [NEIGH_VAR_BASE_REACHABLE_TIME] = 30 * HZ,
> [NEIGH_VAR_DELAY_PROBE_TIME] = 5 * HZ,
> [NEIGH_VAR_GC_STALETIME] = 60 * HZ,
> - [NEIGH_VAR_QUEUE_LEN_BYTES] = 64 * 1024,
> + [NEIGH_VAR_QUEUE_LEN_BYTES] = SK_WMEM_MAX,
> [NEIGH_VAR_PROXY_QLEN] = 64,
> [NEIGH_VAR_ANYCAST_DELAY] = 1 * HZ,
> [NEIGH_VAR_PROXY_DELAY] = (8 * HZ) / 10,
> diff --git a/net/ipv6/ndisc.c b/net/ipv6/ndisc.c
> index 5e338eb89509b1df6ebd060f8bd19fcb4b86fe05..266a530414d7be4f1e7be922e465bbab46f7cbac 100644
> --- a/net/ipv6/ndisc.c
> +++ b/net/ipv6/ndisc.c
> @@ -127,7 +127,7 @@ struct neigh_table nd_tbl = {
> [NEIGH_VAR_BASE_REACHABLE_TIME] = ND_REACHABLE_TIME,
> [NEIGH_VAR_DELAY_PROBE_TIME] = 5 * HZ,
> [NEIGH_VAR_GC_STALETIME] = 60 * HZ,
> - [NEIGH_VAR_QUEUE_LEN_BYTES] = 64 * 1024,
> + [NEIGH_VAR_QUEUE_LEN_BYTES] = SK_WMEM_MAX,
> [NEIGH_VAR_PROXY_QLEN] = 64,
> [NEIGH_VAR_ANYCAST_DELAY] = 1 * HZ,
> [NEIGH_VAR_PROXY_DELAY] = (8 * HZ) / 10,
>
>
--
Florian
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