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net: refine {udp|tcp|sctp}_mem limits 

Current tcp/udp/sctp global memory limits are not taking into account
hugepages allocations, and allow 50% of ram to be used by buffers of a
single protocol [ not counting space used by sockets / inodes ...]

Lets use nr_free_buffer_pages() and allow a default of 1/8 of kernel ram
per protocol, and a minimum of 128 pages.
Heavy duty machines sysadmins probably need to tweak limits anyway.


References: https://bugzilla.stlinux.com/show_bug.cgi?id=38032
Reported-by: starlight <starlight@binnacle.cx>
Suggested-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Eric Dumazet <eric.dumazet@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
This commit is contained in:
Eric Dumazet 2011-07-07 00:27:05 -07:00 committed by David S. Miller
parent eebb02b1f0
commit f03d78db65
3 changed files with 5 additions and 26 deletions
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10
net/ipv4/tcp.c
View File

@ -3220,7 +3220,7 @@ __setup("thash_entries=", set_thash_entries);
void __init tcp_init(void)
{
struct sk_buff *skb = NULL;
unsigned long nr_pages, limit;
unsigned long limit;
int i, max_share, cnt;
unsigned long jiffy = jiffies;
@ -3277,13 +3277,7 @@ void __init tcp_init(void)
sysctl_tcp_max_orphans = cnt / 2;
sysctl_max_syn_backlog = max(128, cnt / 256);
/* 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.
*/
nr_pages = totalram_pages - totalhigh_pages;
limit = min(nr_pages, 1UL<<(28-PAGE_SHIFT)) >> (20-PAGE_SHIFT);
limit = (limit * (nr_pages >> (20-PAGE_SHIFT))) >> (PAGE_SHIFT-11);
limit = nr_free_buffer_pages() / 8;
limit = max(limit, 128UL);
sysctl_tcp_mem[0] = limit / 4 * 3;
sysctl_tcp_mem[1] = limit;

10
net/ipv4/udp.c
View File

@ -2209,16 +2209,10 @@ void __init udp_table_init(struct udp_table *table, const char *name)
void __init udp_init(void)
{
unsigned long nr_pages, limit;
unsigned long limit;
udp_table_init(&udp_table, "UDP");
/* Set the pressure threshold up by the same strategy of TCP. It is 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.
*/
nr_pages = totalram_pages - totalhigh_pages;
limit = min(nr_pages, 1UL<<(28-PAGE_SHIFT)) >> (20-PAGE_SHIFT);
limit = (limit * (nr_pages >> (20-PAGE_SHIFT))) >> (PAGE_SHIFT-11);
limit = nr_free_buffer_pages() / 8;
limit = max(limit, 128UL);
sysctl_udp_mem[0] = limit / 4 * 3;
sysctl_udp_mem[1] = limit;

11
net/sctp/protocol.c
View File

@ -1058,7 +1058,6 @@ SCTP_STATIC __init int sctp_init(void)
int status = -EINVAL;
unsigned long goal;
unsigned long limit;
unsigned long nr_pages;
int max_share;
int order;
@ -1148,15 +1147,7 @@ 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 initializes the data in sctpv6_prot too
* Unabashedly stolen from tcp_init
*/
nr_pages = totalram_pages - totalhigh_pages;
limit = min(nr_pages, 1UL<<(28-PAGE_SHIFT)) >> (20-PAGE_SHIFT);
limit = (limit * (nr_pages >> (20-PAGE_SHIFT))) >> (PAGE_SHIFT-11);
limit = nr_free_buffer_pages() / 8;
limit = max(limit, 128UL);
sysctl_sctp_mem[0] = limit / 4 * 3;
sysctl_sctp_mem[1] = limit;