netdev - Re: small RPS cache for fragments?

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Message-ID: <m2aaelypbp.fsf@firstfloor.org>
Date:	Tue, 17 May 2011 14:44:42 -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:
>
> OK but do we have workloads actually needing this optimization at all ?

That's a good a question.
>
> (IP defrag hits a read_lock(&ip4_frags.lock)), so maybe steer all frags
> on a given cpu ?)

Couldn't the lock just be replaced with a hashed or bitmap lock or 
bit in low bits of pointer lock?

iirc it just protects the heads of the hash table.

They're not rwlocks, but especially if the locking was more finegrained
that's likely not needed anymore.

-Andi

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