From: John Heffner Date: Tue, 17 Apr 2007 21:44:06 +0000 (-0700) Subject: Fix errors in tcp_mem[] calculations. X-Git-Tag: v2.6.20.11~20 X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=3300bb14330a902331bcdfd0f69d9b0945585c51;p=thirdparty%2Fkernel%2Fstable.git Fix errors in tcp_mem[] calculations. In 2.6.18 a change was made to the tcp_mem[] calculations, but this causes regressions for some folks up to 2.6.20 The following fix to smooth out the calculation from the pending 2.6.21 tree by John Heffner fixes the problem for these folks. [TCP]: Fix tcp_mem[] initialization. Change tcp_mem initialization function. The fraction of total memory is now a continuous function of memory size, and independent of page size. Signed-off-by: John Heffner Signed-off-by: David S. Miller Signed-off-by: Greg Kroah-Hartman --- diff --git a/net/ipv4/tcp.c b/net/ipv4/tcp.c index ebe9d0d238fd2..4a71b310f9a60 100644 --- a/net/ipv4/tcp.c +++ b/net/ipv4/tcp.c @@ -2457,11 +2457,18 @@ void __init tcp_init(void) sysctl_max_syn_backlog = 128; } - /* Allow no more than 3/4 kernel memory (usually less) allocated to TCP */ - sysctl_tcp_mem[0] = (1536 / sizeof (struct inet_bind_hashbucket)) << order; - sysctl_tcp_mem[1] = sysctl_tcp_mem[0] * 4 / 3; + /* 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. + */ + limit = min(nr_all_pages, 1UL<<(28-PAGE_SHIFT)) >> (20-PAGE_SHIFT); + limit = (limit * (nr_all_pages >> (20-PAGE_SHIFT))) >> (PAGE_SHIFT-11); + limit = max(limit, 128UL); + sysctl_tcp_mem[0] = limit / 4 * 3; + sysctl_tcp_mem[1] = limit; sysctl_tcp_mem[2] = sysctl_tcp_mem[0] * 2; + /* Set per-socket limits to no more than 1/128 the pressure threshold */ limit = ((unsigned long)sysctl_tcp_mem[1]) << (PAGE_SHIFT - 7); max_share = min(4UL*1024*1024, limit);