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  PHC 
Open Source and information security mailing list archives
Hash Suite for Android: free password hash cracker in your pocket
[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]
Date:	Wed, 5 Mar 2014 09:13:30 +0800
From:	Ding Tianhong <>
To:	Joe Perches <>
CC:	Patrick McHardy <>,
	"David S. Miller" <>,
	Julia Lawall <>,
	Netdev <>
Subject: Re: [PATCH net-next] vlan: slight optimization for vlan

On 2014/3/4 23:50, Joe Perches wrote:
> On Tue, 2014-03-04 at 18:47 +0800, Ding Tianhong wrote:
>> Ether_addr_equal_64bits is more efficient than ether_addr_equal, and
>> can be used when each argument is an array within a structure that
>> contains at least two bytes of data beyond the array, so it is safe
>> to use it for vlan.
> Perhaps I wasn't clear or perhaps you simply disagree,
> (which is certainly your right), but I think that
> ether_addr_equal_64bits should _only_ be used in
> performance sensitive paths because using it requires
> a person/script to analyze surrounding structures to
> ensure 2 bytes exist after the address.
> I don't think that vlan_dev_(open|stop|set_mac_address)
> are performance sensitive paths.
> vlan_do_receive, absolutely yes.
> Is the vlan_device_event:NETDEV_CHANGEADDR:vlan_sync_address
> path that frequent?  Maybe.
>> On a simple test by iperf, it reduces the CPU %system time from 14% to 12%.

Totally agree with you, use the XXX_64bits in slow path make no sense, thanks a lot.

>> According Joe's suggestion, maybe it'd be faster to add an unlikely to
>> the test for PCKET_OTHERHOST, so I add it and see whether the performance
>> could be better, but the differences is so small and negligible, maybe my
>> test case is not effective enough, but I still add the unlikely and wait to
>> hear more opinions.:)
> A separate patch for the unlikely would likely be better,
> but I wonder what your test case is.
> I presume a single stream of identical vlan PACKET_OTHERHOST
> packets is atypical.



To unsubscribe from this list: send the line "unsubscribe netdev" in
the body of a message to
More majordomo info at

Powered by blists - more mailing lists