netdev - Re: [PATCH net-next] vlan: Add GRO support for non hardware accelerated vlan

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:	Fri, 29 May 2015 23:48:08 +0900
From:	Toshiaki Makita <toshiaki.makita1@...il.com>
To:	Eric Dumazet <eric.dumazet@...il.com>,
	Toshiaki Makita <makita.toshiaki@....ntt.co.jp>
CC:	"David S . Miller" <davem@...emloft.net>,
	Patrick McHardy <kaber@...sh.net>, netdev@...r.kernel.org
Subject: Re: [PATCH net-next] vlan: Add GRO support for non hardware accelerated
 vlan

On 15/05/28 (木) 21:02, Eric Dumazet wrote:
> On Thu, 2015-05-28 at 20:17 +0900, Toshiaki Makita wrote:
>> Currently packets with non-hardware-accelerated vlan cannot be handled
>> by GRO. This causes low performance for 802.1ad and stacked vlan, as their
>> vlan tags are currently not stripped by hardware.
>>
>> This patch adds GRO support for non-hardware-accelerated vlan and
>> improves receive performance of them.
>
> Very nice patch !
>
>>
>> Signed-off-by: Toshiaki Makita <makita.toshiaki@....ntt.co.jp>
>> ---
>>   net/8021q/vlan.c | 94 ++++++++++++++++++++++++++++++++++++++++++++++++++++++++
>>   1 file changed, 94 insertions(+)
>>
>> diff --git a/net/8021q/vlan.c b/net/8021q/vlan.c
>> index 59555f0..0a9e8e1 100644
>> --- a/net/8021q/vlan.c
>> +++ b/net/8021q/vlan.c
>> @@ -618,6 +618,90 @@ out:
>>   	return err;
>>   }
>>
>> +		vhdr2 = (struct vlan_hdr *)(p->data + off_vlan);
>> +		if (memcmp(vhdr, vhdr2, VLAN_HLEN))
>> +			NAPI_GRO_CB(p)->same_flow = 0;
>> +	}
>
>
> This memcmp() is quite expensive, you better use a helper like :
>
> /* vlan header only guaranteed to be 16bit aligned */
> static bool vlan_hdr_compare(const struct vlan_hdr *h1, const struct vlan_hdr *h2)
> {
> #if defined(CONFIG_HAVE_EFFICIENT_UNALIGNED_ACCESS)
> 	return *(u32 *)h1 != *(u32 *)h2;
> #else
> 	return (((__force u32)h1->h_vlan_TCI ^ (__force u32)h2->h_vlan_TCI) |
> 		((__force u32)h1->h_vlan_encapsulated_proto ^
> 		 (__force u32)h2->h_vlan_encapsulated_proto)) != 0;
> #endif
> }

Hi Eric,

Thank you for your reviewing.
Indeed, memcmp() is not good for performance.
I'll include your feedback in v2.

Thanks,
Toshiaki Makita
--
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