netdev - Re: [PATCH 3/7] flow: allocate hash table for online cpus only

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] [day] [month] [year] [list]

Message-ID: <4BB34DC8.7080903@iki.fi>
Date:	Wed, 31 Mar 2010 16:27:36 +0300
From:	Timo Teräs <timo.teras@....fi>
To:	Rusty Russell <rusty@...tcorp.com.au>
CC:	Herbert Xu <herbert@...dor.apana.org.au>, netdev@...r.kernel.org
Subject: Re: [PATCH 3/7] flow: allocate hash table for online cpus only

Rusty Russell wrote:
> On Tue, 30 Mar 2010 10:42:55 pm Herbert Xu wrote:
>> On Mon, Mar 29, 2010 at 05:12:40PM +0300, Timo Teras wrote:
>>> Instead of unconditionally allocating hash table for all possible
>>> cpu's, allocate it only for online cpu's and release related
>>> memory if cpu goes down.
>>>
>>> Signed-off-by: Timo Teras <timo.teras@....fi>
>> Hmm that's where we started but then Rusty changed it back in 2004:
>>
>> So I'd like to hear his opinion on changing it back again.
> 
> It was pretty unique at the time, it no longer is, so the arguments are less
> compelling IMHO.
> 
> However, we can now use a dynamic percpu variable and get it as a real
> per-cpu thing (which currently means it *will* be for every available cpu,
> not just online ones).  Haven't thought about it, but that change might be
> worth considering instead?

I did convert most of the static percpu variables to a struct which
is allocated dynamically using alloc_percpu. See:
 http://marc.info/?l=linux-netdev&m=127003066905912&w=2

This patch is on top of that, to avoid allocating the larger hash
table unconditionally as amount of possible cpu's can be large.
If you take a look at the actual patch to add back the hash allocation
for only 'online' cpu's, it's not that complicated IMHO:
 http://marc.info/?l=linux-netdev&m=126987200927472&w=2

--
To unsubscribe from this list: send the line "unsubscribe netdev" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html