linux-kernel - Re: [PATCH 1/8] drivers/random: Cache align ip

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Date:	Wed, 16 Mar 2011 14:55:07 -0500
From:	Matt Mackall <mpm@...enic.com>
To:	Eric Dumazet <eric.dumazet@...il.com>
Cc:	Hugh Dickins <hughd@...gle.com>,
	George Spelvin <linux@...izon.com>, penberg@...helsinki.fi,
	herbert@...dor.hengli.com.au, linux-mm@...ck.org,
	linux-kernel@...r.kernel.org
Subject: Re: [PATCH 1/8] drivers/random: Cache align ip_random better

On Wed, 2011-03-16 at 20:26 +0100, Eric Dumazet wrote:
> > I think this alignment exists to minimize the number of cacheline
> > bounces on SMP as this can be a pretty hot structure in the network
> > stack. It could probably benefit from a per-cpu treatment.
> > 
> 
> Well, this is a mostly read area of memory, dirtied every 5 minutes.
> 
> Compare this to 'jiffies' for example ;)
> 
> What could be done is to embed 'ip_cnt' inside ip_keydata[0] for
> example, to avoid wasting a cache line for one bit ;)
> 
> 
> c1606c40 b ip_cnt
> <hole>
> c1606c80 b ip_keydata

Yeah. I actually think we're due for rethinking this entire process. It
dates back to when we introduced syncookies in the 90s and it shows. The
fact that we've started abusing it for other things doesn't help.

-- 
Mathematics is the supreme nostalgia of our time.


--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/