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Date: Mon, 06 Apr 2009 14:07:34 +0200 From: Patrick McHardy <kaber@...sh.net> To: Stephen Hemminger <shemminger@...tta.com> CC: Eric Dumazet <dada1@...mosbay.com>, David Miller <davem@...emloft.net>, Rick Jones <rick.jones2@...com>, netdev@...r.kernel.org, netfilter-devel@...r.kernel.org Subject: Re: [PATCH] netfilter: finer grained nf_conn locking Stephen Hemminger wrote: > On Mon, 30 Mar 2009 21:57:15 +0200 > Eric Dumazet <dada1@...mosbay.com> wrote: > >> On normal machines, (no debugging spinlocks), patch uses an embedded >> spinlock. We probably can use this even on 32bit kernels, considering >> previous patch removed the rcu_head (8 bytes on 32bit arches) from >> nf_conn :) >> >> if LOCKDEP is on, size of a spinlock is 64 bytes on x86_64. >> Adding a spinlock on each nf_conn would be too expensive. In this >> case, an array of spinlock is a good compromise, as done in >> IP route cache, tcp ehash, ... >> >> I agree sizing of this hash table is not pretty, and should be >> a generic kernel service (I wanted such service for futexes for example) >> > > IMO having different locking based on lockdep and architecture is an invitation > to future obscure problems. Perhaps some other locking method or shrinking > ct entry would be better. I agree. Do people enable lockdep on production machines? Otherwise I'd say the size increase doesn't really matter. -- 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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