Commit f03d78db authored by Eric Dumazet's avatar Eric Dumazet Committed by David S. Miller
Browse files

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: default avatarstarlight <starlight@binnacle.cx>
Suggested-by: default avatarAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: default avatarEric Dumazet <eric.dumazet@gmail.com>
Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
parent eebb02b1

net/ipv4/tcp.c

+2 −8
Original line number Diff line number Diff line
@@ -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;

net/ipv4/udp.c

+2 −8
Original line number Diff line number Diff line
@@ -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;

net/sctp/protocol.c

+1 −10
Original line number Diff line number Diff line
@@ -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;

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