[SCTP]: Rewrite of sctp buffer management code

This patch introduces autotuning to the sctp buffer management code
similar to the TCP.  The buffer space can be grown if the advertised
receive window still has room.  This might happen if small message
sizes are used, which is common in telecom environmens.
New tunables are introduced that provide limits to buffer growth
and memory pressure is entered if to much buffer spaces is used.

Signed-off-by: Neil Horman <nhorman@tuxdriver.com>
Signed-off-by: Vlad Yasevich <vladislav.yasevich@hp.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 32 insertions, 0 deletions

diff --git a/net/sctp/protocol.c b/net/sctp/protocol.c
index 3d036cdfae4..957c118a606 100644
--- a/net/sctp/protocol.c
+++ b/net/sctp/protocol.c
@@ -51,6 +51,7 @@
 #include <linux/netdevice.h>
 #include <linux/inetdevice.h>
 #include <linux/seq_file.h>
+#include <linux/bootmem.h>
 #include <net/protocol.h>
 #include <net/ip.h>
 #include <net/ipv6.h>
@@ -82,6 +83,10 @@ static struct sctp_af *sctp_af_v6_specific;
 struct kmem_cache *sctp_chunk_cachep __read_mostly;
 struct kmem_cache *sctp_bucket_cachep __read_mostly;
 
+extern int sysctl_sctp_mem[3];
+extern int sysctl_sctp_rmem[3];
+extern int sysctl_sctp_wmem[3];
+
 /* Return the address of the control sock. */
 struct sock *sctp_get_ctl_sock(void)
 {
@@ -987,6 +992,8 @@ SCTP_STATIC __init int sctp_init(void)
         int i;
         int status = -EINVAL;
         unsigned long goal;
+        unsigned long limit;
+        int max_share;
         int order;
 
         /* SCTP_DEBUG sanity check. */
@@ -1077,6 +1084,31 @@ SCTP_STATIC __init int sctp_init(void)
         /* Initialize handle used for association ids. */
         idr_init(&sctp_assocs_id);
 
+        /* Set the pressure threshold to be a fraction of global memory that
+         * is up to 1/2 at 256 MB, decreasing toward zero with the amount of
+         * memory, with a floor of 128 pages.
+         * Note this initalizes the data in sctpv6_prot too
+         * Unabashedly stolen from tcp_init
+         */
+        limit = min(num_physpages, 1UL<<(28-PAGE_SHIFT)) >> (20-PAGE_SHIFT);
+        limit = (limit * (num_physpages >> (20-PAGE_SHIFT))) >> (PAGE_SHIFT-11);
+        limit = max(limit, 128UL);
+        sysctl_sctp_mem[0] = limit / 4 * 3;
+        sysctl_sctp_mem[1] = limit;
+        sysctl_sctp_mem[2] = sysctl_sctp_mem[0] * 2;
+
+        /* Set per-socket limits to no more than 1/128 the pressure threshold*/
+        limit = (sysctl_sctp_mem[1]) << (PAGE_SHIFT - 7);
+        max_share = min(4UL*1024*1024, limit);
+
+        sysctl_sctp_rmem[0] = PAGE_SIZE; /* give each asoc 1 page min */
+        sysctl_sctp_rmem[1] = (1500 *(sizeof(struct sk_buff) + 1));
+        sysctl_sctp_rmem[2] = max(sysctl_sctp_rmem[1], max_share);
+
+        sysctl_sctp_wmem[0] = SK_STREAM_MEM_QUANTUM;
+        sysctl_sctp_wmem[1] = 16*1024;
+        sysctl_sctp_wmem[2] = max(64*1024, max_share);
+
         /* Size and allocate the association hash table.
          * The methodology is similar to that of the tcp hash tables.
          */