Re: [PATCH] fix up sysctl_tcp_mem initialization
David Miller wrote: However, I wonder if we want to set this differently than the way this patch does it. Depending on how far off the memory size is from a power of two (exactly equal to a power of two is the worst case), and if total memory 128M, it can be substantially less than 3/4. Longer term, yes, probably a better way exists. So you concern is that when we round to a power of 2 like we do now, we often mis-shoot? I'm not that concerned about it, but basically yes, there are big (x2) jumps on power-of-two memory size boundaries. There's also a bigger (x8) discontinuity at 128k pages. It could be smoother. -John - To unsubscribe from this list: send the line unsubscribe netdev in the body of a message to [EMAIL PROTECTED] More majordomo info at http://vger.kernel.org/majordomo-info.html
[PATCH] fix up sysctl_tcp_mem initialization
The initial values of sysctl_tcp_mem are sometimes greater than the total memory in the system (particularly on SMP systems). This patch ensures that tcp_mem[2] is always = 3/4 nr_kernel_pages. However, I wonder if we want to set this differently than the way this patch does it. Depending on how far off the memory size is from a power of two (exactly equal to a power of two is the worst case), and if total memory 128M, it can be substantially less than 3/4. -John Fix up tcp_mem initiail settings to take into account the size of the hash entries (different on SMP and non-SMP systems). Signed-off-by: John Heffner [EMAIL PROTECTED] --- commit d4ef8c8245c0a033622ce9ba9e25d379475254f6 tree 5377b8af0bac3b92161188e7369a84e472b5acb2 parent ea55b7c31b47edf90132baea9a088da3bbe2bb5c author John Heffner [EMAIL PROTECTED] Tue, 14 Nov 2006 14:53:27 -0500 committer John Heffner [EMAIL PROTECTED] Tue, 14 Nov 2006 14:53:27 -0500 net/ipv4/tcp.c |7 --- 1 files changed, 4 insertions(+), 3 deletions(-) diff --git a/net/ipv4/tcp.c b/net/ipv4/tcp.c index 4322318..c05e8ed 100644 --- a/net/ipv4/tcp.c +++ b/net/ipv4/tcp.c @@ -2316,9 +2316,10 @@ void __init tcp_init(void) sysctl_max_syn_backlog = 128; } - sysctl_tcp_mem[0] = 768 order; - sysctl_tcp_mem[1] = 1024 order; - sysctl_tcp_mem[2] = 1536 order; + /* 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; + sysctl_tcp_mem[2] = sysctl_tcp_mem[0] * 2; limit = ((unsigned long)sysctl_tcp_mem[1]) (PAGE_SHIFT - 7); max_share = min(4UL*1024*1024, limit);
Re: [PATCH] fix up sysctl_tcp_mem initialization
From: John Heffner [EMAIL PROTECTED] Date: Tue, 14 Nov 2006 15:02:05 -0500 The initial values of sysctl_tcp_mem are sometimes greater than the total memory in the system (particularly on SMP systems). This patch ensures that tcp_mem[2] is always = 3/4 nr_kernel_pages. This is a genuine bug fix so I'll apply this, thanks for taking care of these corner-case bugs in TCP sizing Jeff. However, I wonder if we want to set this differently than the way this patch does it. Depending on how far off the memory size is from a power of two (exactly equal to a power of two is the worst case), and if total memory 128M, it can be substantially less than 3/4. Longer term, yes, probably a better way exists. So you concern is that when we round to a power of 2 like we do now, we often mis-shoot? - To unsubscribe from this list: send the line unsubscribe netdev in the body of a message to [EMAIL PROTECTED] More majordomo info at http://vger.kernel.org/majordomo-info.html
