netdev - Re: [PATCH net-next 3/3] net: allow to leave the buffer fragmented in skb_cow

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]

Date:	Thu, 07 Nov 2013 11:01:10 +0100
From:	Mathias Krause <mathias.krause@...unet.com>
To:	Herbert Xu <herbert@...dor.apana.org.au>
CC:	"David S. Miller" <davem@...emloft.net>,
	Steffen Klassert <steffen.klassert@...unet.com>,
	Dmitry Tarnyagin <dmitry.tarnyagin@...kless.no>,
	netdev@...r.kernel.org
Subject: Re: [PATCH net-next 3/3] net: allow to leave the buffer fragmented
 in skb_cow_data()

On 07.11.2013 10:01, Herbert Xu wrote:
> On Thu, Nov 07, 2013 at 09:55:34AM +0100, Mathias Krause wrote:
>> Indeed. I want to avoid the costly memcpy() on the CPU serving the NIC
>> interrupt, as that is a bottleneck in my setup. The packet processing --
>> encrypting/decrypting of ESP packets -- gets mostly parallelized via
>> pcrypt, so that's fine. But the initial network processing, i.e. getting
>> to pcrypt, is what's throttling the throughput currently. (RPS only
>> partly solves this problem as for the ESP receive path most traffic ends
>> up on the same flow).
> 
> How about this: instead of doing in-place encryption/decryption
> let's allocate a new destination buffer and encrypt/decrypt into
> it.  Then we essentially get the copy for free.
> 
> So instead of modifying skb_cow_data you can change esp4.c, etc.

That might be another option. But I fear it might affect performance due
to caching or NUMA effects. :/

I'll think about it and will try to investigate both approaches.


Thanks,
Mathias
--
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