netdev - Re: More prefetch fall-out

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Message-Id: <20110522.181503.1446789103624635529.davem@davemloft.net>
Date:	Sun, 22 May 2011 18:15:03 -0400 (EDT)
From:	David Miller <davem@...emloft.net>
To:	torvalds@...ux-foundation.org
Cc:	netdev@...r.kernel.org
Subject: Re: More prefetch fall-out

From: Linus Torvalds <torvalds@...ux-foundation.org>
Date: Sun, 22 May 2011 10:49:11 -0700

> However, one of the breakages is <linux/skbuff.h> that does its own
> list-walking functions ("skb_queue_walk*"), and they do prefetching.
> So now I have the option to either just add <linux/prefetch.h> to that
> file, or remove the prefetches. And you're the one that said that the
> prefetches in the networking code were annoying.
> 
> So should the skb queues use prefetching? I have a hard time judging.
> Are those lists usually long? Is the loop usually large enough that
> there is any point to prefetching the next entry?

Please just remove the prefetches.

Those are modelled after list.h as I intend to eventually convert
SKB list handling to "struct list_head" but we're not there yet.

Therefore if we kill prefetches from list.h we should kill it from
these things in skbuff.h too.

Thanks!
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