netdev - Re: [PATCH] tcp: Fix sysctl_tcp_max_orphans when PAGE

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Date:	Thu, 26 Aug 2010 06:45:31 +0200
From:	Eric Dumazet <eric.dumazet@...il.com>
To:	Anton Blanchard <anton@...ba.org>
Cc:	David Miller <davem@...emloft.net>, netdev@...r.kernel.org,
	miltonm@....com
Subject: Re: [PATCH] tcp: Fix sysctl_tcp_max_orphans when PAGE_SIZE != 4k

Le jeudi 26 août 2010 à 10:38 +1000, Anton Blanchard a écrit :
> Hi Dave,
> 
> > Yeah, something like the following, Anton?
> 
> Thanks! I tested on a 512GB box. One thing:
> 
> # cat /proc/sys/net/ipv4/tcp_max_syn_backlog 
> 128
> 
> We probably want to use max():
> 
> > -	sysctl_max_syn_backlog = min(128, cnt / 256);
> > +	sysctl_max_syn_backlog = max(128, cnt / 256);
> 

I believe I make this min()/max() error once per week, sorry ;)

In my mind, I say "I want a minimum value of 128", then I write :

val = min(128, val);

instead of 

val = max(128, val);

Oh well...

> With that change:
> 
> # cat /proc/sys/net/ipv4/tcp_max_orphans 
> 262144
> # cat /proc/sys/net/ipv4/tcp_max_tw_buckets
> 262144
> # cat /proc/sys/net/ipv4/tcp_max_syn_backlog 
> 2048
> 
> 
> Tested-by: Anton Blanchard <anton@...ba.org>
> 
> Anton

Seems pretty good to me, thanks !

BTW, we now auto-limit ehash to 512*1024 slots, so you probably have
same results on a 128GB or 4096GB machine ;)



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