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From: Eric Dumazet <eric.dumazet@gmail.com>
To: Ben Hutchings <bhutchings@solarflare.com>
Cc: Thomas Gleixner <tglx@linutronix.de>,
	David Miller <davem@davemloft.net>,
	Tom Herbert <therbert@google.com>,
	linux-kernel@vger.kernel.org, netdev@vger.kernel.org,
	linux-net-drivers@solarflare.com
Subject: Re: [PATCH 2/2] lib: cpu_rmap: CPU affinity reverse-mapping
Date: Tue, 04 Jan 2011 23:19:02 +0100	[thread overview]
Message-ID: <1294179542.3420.13.camel@edumazet-laptop> (raw)
In-Reply-To: <1294178690.3636.49.camel@bwh-desktop>

Le mardi 04 janvier 2011 à 22:04 +0000, Ben Hutchings a écrit :

> get_rps_cpu() will need to read from an arbitrary entry in cpu_rmap (not
> the current CPU's entry) for each new flow and for each flow that went
> idle for a while.  That's not fast path but it is part of the data path,
> not the control path.
> 

Hmm, I call this fast path :(

> > Cache lines dont matter. I was not concerned about speed but memory
> > needs.
> > 
> > NR_CPUS can be 4096 on some distros, that means a 32Kbyte allocation.
> > 
> > Really, you'll have to have very strong arguments to introduce an
> > [NR_CPUS] array in the kernel today.
> 
> I could replace this with a pointer to an array of size
> num_possible_cpus().  But I think per_cpu is wrong here.

Yes, an dynamic array is acceptable

You probably mean nr_cpu_ids 

      reply	other threads:[~2011-01-04 22:19 UTC|newest]

Thread overview: 11+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2011-01-04 19:37 [PATCH 0/2] IRQ affinity reverse-mapping Ben Hutchings
2011-01-04 19:38 ` [PATCH 1/2] genirq: Add IRQ affinity notifiers Ben Hutchings
2011-01-14 19:47   ` Thomas Gleixner
2011-01-14 20:06     ` Ben Hutchings
2011-01-14 20:40       ` Thomas Gleixner
2011-01-04 19:39 ` [PATCH 2/2] lib: cpu_rmap: CPU affinity reverse-mapping Ben Hutchings
2011-01-04 21:17   ` Eric Dumazet
2011-01-04 21:23     ` Ben Hutchings
2011-01-04 21:45       ` Eric Dumazet
2011-01-04 22:04         ` Ben Hutchings
2011-01-04 22:19           ` Eric Dumazet [this message]

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