From: Eric Dumazet <eric.dumazet@gmail.com>
To: "Eric W. Biederman" <ebiederm@xmission.com>
Cc: David Miller <davem@davemloft.net>,
alexander.duyck@gmail.com, netdev@vger.kernel.org
Subject: Re: [PATCH 00/16] Remove the ipv4 routing cache
Date: Fri, 27 Jul 2012 18:28:53 +0200 [thread overview]
Message-ID: <1343406533.2626.13104.camel@edumazet-glaptop> (raw)
In-Reply-To: <87mx2l41hl.fsf@xmission.com>
On Fri, 2012-07-27 at 09:23 -0700, Eric W. Biederman wrote:
> I am familiar. But does hardware prefetching make a difference
> if your object is less than 64 bytes?
>
Apparently yes, if the prefetch touches a dirtied neighbour cache line.
> I don't believe only allocating 64 bytes will be a problem,
> as no one else well be dirtying your cache line.
>
> I suppose you could run into pathologies where your object
> is 3*64 bytes in size, but your expression doesn't handle
> that case either.
>
Sure, but in most cases fib objects are under 128 bytes.
> The other alternative to guarantee very good cache behavior is
> to ensure you are allocating a power of two size up to some limit,
> perhaps page size.
>
Good idea.
> My point is the magic 128 likely requires an explicatory comment and I
> think the net result is you have encoded something fragile that is good
> for testing but that will in the fullness of time do strange things that
> will be easy to overlook.
Sure, I'll send a v2, thanks.
next prev parent reply other threads:[~2012-07-27 16:28 UTC|newest]
Thread overview: 51+ messages / expand[flat|nested] mbox.gz Atom feed top
2012-07-20 21:25 [PATCH 00/16] Remove the ipv4 routing cache David Miller
2012-07-20 22:05 ` Eric Dumazet
2012-07-20 22:42 ` Eric Dumazet
2012-07-20 22:50 ` David Miller
2012-07-20 22:54 ` David Miller
2012-07-20 23:13 ` David Miller
2012-07-21 5:40 ` Eric Dumazet
2012-07-22 7:47 ` Vijay Subramanian
2012-07-22 19:42 ` David Miller
2012-07-23 0:39 ` David Miller
2012-07-23 7:15 ` Eric Dumazet
2012-07-23 17:54 ` Paweł Staszewski
2012-07-23 20:10 ` David Miller
2012-07-26 17:02 ` Eric Dumazet
2012-07-25 23:02 ` Alexander Duyck
2012-07-25 23:17 ` David Miller
2012-07-25 23:39 ` David Miller
2012-07-26 0:54 ` David Miller
2012-07-26 2:30 ` Alexander Duyck
2012-07-26 5:32 ` David Miller
2012-07-26 8:13 ` Eric Dumazet
2012-07-26 8:18 ` David Miller
2012-07-26 8:27 ` Eric Dumazet
2012-07-26 8:47 ` David Miller
2012-07-26 9:12 ` Eric Dumazet
2012-07-26 17:18 ` Alexander Duyck
2012-07-26 17:30 ` Eric Dumazet
2012-07-26 17:36 ` Eric Dumazet
2012-07-26 17:43 ` Eric Dumazet
2012-07-26 17:48 ` Eric Dumazet
2012-07-26 18:26 ` Alexander Duyck
2012-07-26 21:06 ` David Miller
2012-07-26 22:03 ` Alexander Duyck
2012-07-26 22:13 ` Stephen Hemminger
2012-07-26 22:19 ` Eric Dumazet
2012-07-26 22:48 ` David Miller
2012-07-26 22:53 ` David Miller
2012-07-27 2:14 ` Alexander Duyck
2012-07-27 3:08 ` David Miller
2012-07-27 6:02 ` David Miller
2012-07-27 10:01 ` Eric Dumazet
2012-07-27 14:53 ` Eric W. Biederman
2012-07-27 15:12 ` Eric Dumazet
2012-07-27 16:23 ` Eric W. Biederman
2012-07-27 16:28 ` Eric Dumazet [this message]
2012-07-27 19:06 ` Alexander Duyck
2012-07-28 4:15 ` David Miller
2012-07-28 5:45 ` Alexander Duyck
2012-07-26 18:06 ` Alexander Duyck
2012-07-26 21:00 ` David Miller
2012-07-26 20:59 ` David Miller
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