netdev - Re: small RPS cache for fragments?

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Message-ID: <m2vcx9x9v7.fsf@firstfloor.org>
Date:	Tue, 17 May 2011 15:03:56 -0700
From:	Andi Kleen <andi@...stfloor.org>
To:	Eric Dumazet <eric.dumazet@...il.com>
Cc:	David Miller <davem@...emloft.net>, netdev@...r.kernel.org
Subject: Re: small RPS cache for fragments?

Eric Dumazet <eric.dumazet@...il.com> writes:

>> They're not rwlocks, but especially if the locking was more finegrained
>> that's likely not needed anymore.
>
> Well, there is the rehashing stuff, and this locks the whole table.
>
> Not easy to switch to rcu or something like that.

No need to switch to RCU, just a more finegrained bucket lock.

If you move a chain between queues you just lock both for the move.
It sounds easy enough. I should probably just code it up.

>
> Anyway I hardly use frags here at work, so never considered it was a
> field to spend time ;)

Yes that's the problem. On the other hand most scalability problems hurt
sooner or later, so sometimes it's good to fix them in advance.

-Andi

-- 
ak@...ux.intel.com -- Speaking for myself only
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