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Message-ID: <20101001203022.GA28486@1wt.eu> Date: Fri, 1 Oct 2010 22:30:22 +0200 From: Willy Tarreau <w@....eu> To: Robin Holt <holt@....com> Cc: "David S. Miller" <davem@...emloft.net>, Alexey Kuznetsov <kuznet@....inr.ac.ru>, "Pekka Savola (ipv6)" <pekkas@...core.fi>, James Morris <jmorris@...ei.org>, Hideaki YOSHIFUJI <yoshfuji@...ux-ipv6.org>, Patrick McHardy <kaber@...sh.net>, Vlad Yasevich <vladislav.yasevich@...com>, Sridhar Samudrala <sri@...ibm.com>, linux-kernel@...r.kernel.org, netdev@...r.kernel.org, linux-decnet-user@...ts.sourceforge.net, linux-sctp@...r.kernel.org Subject: Re: sysctl_{tcp,udp,sctp}_mem overflow on 16TB system. Hello Robin, On Fri, Oct 01, 2010 at 02:39:58PM -0500, Robin Holt wrote: > > On a 16TB system, we noticed that sysctl_tcp_mem[2] and sysctl_udp_mem[2] > were negative. Code review indicates that the same should occur with > sysctl_sctp_mem[2]. > > There are a couple ways we could address this. The one which appears most > reasonable would be to change the struct proto defintion for sysctl_mem > from an int to a long and handle all the associated fallout. > > An alternative is to limit the calculation to 1/2 INT_MAX. The downside > being that the administrator could not tune the system to use more than > INT_MAX memory when much more is available. > > Is there a compelling reason to not change the structure's definition > over to longs instead of ints and deal with the fallout from that change? Could we not see it differently ? => is there any reason someone would want to assign more than 8 TB of RAM to the network buffers in the near future ? Even at 100 Gbps, that's still 10 minutes of traffic stuck in buffers. Probably that the day we need that large buffers, Linux won't support 32-bit systems anymore and all such limits will have switched to 64-bit. So probably that limiting the value to INT_MAX/2 sounds reasonable ? Regards, Willy -- To unsubscribe from this list: send the line "unsubscribe netdev" in the body of a message to majordomo@...r.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
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