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Date: Wed, 27 Aug 2008 15:09:55 -0700 (PDT) From: David Miller <davem@...emloft.net> To: shemminger@...tta.com Cc: andi@...stfloor.org, davej@...hat.com, netdev@...r.kernel.org, j.w.r.degoede@....nl Subject: Re: cat /proc/net/tcp takes 0.5 seconds on x86_64 From: Stephen Hemminger <shemminger@...tta.com> Date: Wed, 27 Aug 2008 14:48:00 -0700 > I do wonder if having large hash table actually helps? When TCP hash > table gets too big, it means every lookup is a cache miss. Assuming > a busy server with 2000 connections and perfect hash. On a 4G mem x86-64 > we are doing 512K hash entries which is ridiculous. Something like 64K > entries is more than enough. That's true, but it's nearly guaranteed to only be a single cache miss at worst (if the hash function is working) compared to potentially multiple ones if we sized it too small. I really see the only way to move forward is to dynamically size the thing. And nobody has been strong enough to implement that yet :) -- 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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