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Re: Route cache performance under stress

To: "David S. Miller" <davem@xxxxxxxxxx>
Subject: Re: Route cache performance under stress
From: Jamal Hadi <hadi@xxxxxxxxxxxxxxxx>
Date: Mon, 9 Jun 2003 09:22:11 -0400 (EDT)
Cc: xerox@xxxxxxxxxx, sim@xxxxxxxxxxxxx, fw@xxxxxxxxxxxxx, netdev@xxxxxxxxxxx, linux-net@xxxxxxxxxxxxxxx
In-reply-to: <20030609.053218.54202815.davem@xxxxxxxxxx>
References: <20030609072227.R34462@xxxxxxxxxxxxxxxx> <20030609.045547.91327851.davem@xxxxxxxxxx> <20030609080430.I34540@xxxxxxxxxxxxxxxx> <20030609.053218.54202815.davem@xxxxxxxxxx>
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On Mon, 9 Jun 2003, David S. Miller wrote:

>    From: Jamal Hadi <hadi@xxxxxxxxxxxxxxxx>
>    Date: Mon, 9 Jun 2003 08:18:50 -0400 (EDT)
>
>    I found in my tests with a ethernet driver that prefetching the
>    _next_ dma descriptor gave better numbers than prefetching the
>    current one but i didnt spend too much time.
>
> Two issues:
>
> 1) We have some cycles to borrow for head entry, we can make
>    prefetch right before rcu_read_lock()
>
> 2) Ideally, hash chains will not exceed 1 (2 at the max)
>    entries.
>

I dont think youll see much benefit with 1 or 2 entries. I was thinking
more along the lines of people with over 100K entries total;
Let me run with this and get back to you.

cheers,
jamal


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