From: Peter P Waskiewicz Jr <peter.p.waskiewicz.jr@intel•com>
To: "Nelson, Shannon" <shannon.nelson@intel•com>,
Ben Hutchings <bhutchings@solarflare•com>
Cc: "Kirsher, Jeffrey T" <jeffrey.t.kirsher@intel•com>,
"davem@davemloft•net" <davem@davemloft•net>,
"Brandeburg, Jesse" <jesse.brandeburg@intel•com>,
"netdev@vger•kernel.org" <netdev@vger•kernel.org>,
"gospo@redhat•com" <gospo@redhat•com>,
"sassmann@redhat•com" <sassmann@redhat•com>,
"e1000-devel@lists•sourceforge.net"
<e1000-devel@lists•sourceforge.net>
Subject: Re: [net-next 1/8] i40e: main driver core
Date: Thu, 20 Jun 2013 13:52:39 -0700 [thread overview]
Message-ID: <51C36B97.6000000@intel.com> (raw)
In-Reply-To: <FC41C24E35F18A40888AACA1A36F3E4168533F1F@FMSMSX102.amr.corp.intel.com>
On 06/20/2013 01:01 PM, Nelson, Shannon wrote:
>> From: Ben Hutchings [mailto:bhutchings@solarflare•com]
>> Sent: Thursday, June 20, 2013 12:55 PM
>>
>> On Thu, 2013-06-20 at 19:46 +0000, Nelson, Shannon wrote:
>>>> From: Ben Hutchings [mailto:bhutchings@solarflare•com]
>>>> Sent: Wednesday, June 19, 2013 11:13 AM
>>>>
>>>> On Thu, 2013-06-13 at 20:55 -0700, Jeff Kirsher wrote:
>>>>> From: Jesse Brandeburg <jesse.brandeburg@intel•com>
>> [...]
>>>> You should be using rtnl_device_stats64; at 40G a 32-bit counter is
>>>> ridiculous (using this in a 32-bit machine is a bit ridiculous too,
>>>> though...)
>>> You mean rtnl_link_stats64? Sure.
>> Right, yes.
>>
>>> Yes, this driver is really not meant for a 32-bit machine. We've
>>> discussed making sure it would only build for 64-bit, but hadn't quite
>>> gotten around to implementing the restriction. It seems the right
>>> thing to do - would anyone in the community get bent out of shape if
>>> we added that?
>> I'm afraid they probably would.
> Yeah, that was our thought. We're going to try to make sure it at least compiles cleanly, but I'm not sure we'll be able to guarantee useful performance.
>
>> [...]
>>>>> +/**
>>>>> + * i40e_config_rss - Prepare for RSS if used
>>>>> + * @pf: board private structure
>>>>> + **/
>>>>> +static s32 i40e_config_rss(struct i40e_pf *pf)
>>>>> +{
>>>>> + struct i40e_hw *hw = &pf->hw;
>>>>> + u32 lut = 0;
>>>>> + int i, j;
>>>>> + u64 hena;
>>>>> + /* Set of random keys generated using kernel random number
>>>> generator */
>>>>> + static const u32 seed[I40E_PFQF_HKEY_MAX_INDEX + 1] =
>> {0x41b01687,
>>>>> + 0x183cfd8c, 0xce880440, 0x580cbc3c,
>> 0x35897377,
>>>>> + 0x328b25e1, 0x4fa98922, 0xb7d90c14,
>> 0xd5bad70d,
>>>>> + 0xcd15a2c1, 0xe8580225, 0x4a1e9d11,
>> 0xfe5731be};
>>>> Chosen by a fair dice roll?
>>> Well, as fair as /dev/random gets.
>> [...]
>>
>> My point is: once you turn a random choice into a constant, it's no
>> longer random.
Without a pool of statically-allocated random bytes for the seeds, RSS
determinism is impossible. From test to test, workloads would be
completely different, unless your test harness always used the same
source and destination ports, which is not aligned with reality.
-PJ
> Point taken, but we just wanted a random set of bits to start, just as we did in ixgbe.
>
> Thanks,
> sln
>
next prev parent reply other threads:[~2013-06-20 20:52 UTC|newest]
Thread overview: 33+ messages / expand[flat|nested] mbox.gz Atom feed top
2013-06-14 3:55 [net-next 0/8][pull request] Intel Wired LAN Driver Updates Jeff Kirsher
2013-06-14 3:55 ` [net-next 1/8] i40e: main driver core Jeff Kirsher
2013-06-14 5:29 ` Joe Perches
2013-06-16 21:34 ` Nelson, Shannon
2013-06-19 18:12 ` Ben Hutchings
2013-06-20 6:41 ` Nelson, Shannon
2013-06-20 19:46 ` Nelson, Shannon
2013-06-20 19:54 ` Ben Hutchings
2013-06-20 20:01 ` Nelson, Shannon
2013-06-20 20:52 ` Peter P Waskiewicz Jr [this message]
2013-06-19 18:55 ` Stephen Hemminger
2013-06-20 6:41 ` Nelson, Shannon
2013-06-20 20:50 ` Nelson, Shannon
2013-06-14 3:55 ` [net-next 2/8] i40e: transmit, receive, and napi Jeff Kirsher
2013-06-14 3:55 ` [net-next 3/8] i40e: driver ethtool core Jeff Kirsher
2013-06-19 18:27 ` Ben Hutchings
2013-06-20 19:47 ` Nelson, Shannon
2013-06-20 19:59 ` Ben Hutchings
2013-06-20 20:04 ` Nelson, Shannon
2013-06-21 15:39 ` Structured ethtool statistic names Ben Hutchings
2013-06-25 20:46 ` Nelson, Shannon
2013-06-19 18:38 ` [net-next 3/8] i40e: driver ethtool core Stephen Hemminger
2013-06-20 20:52 ` Nelson, Shannon
2013-06-19 18:40 ` Stephen Hemminger
2013-06-20 20:53 ` Nelson, Shannon
2013-06-19 18:41 ` Stephen Hemminger
2013-06-20 20:53 ` Nelson, Shannon
2013-06-14 3:55 ` [net-next 4/8] i40e: driver core headers Jeff Kirsher
2013-06-14 3:55 ` [net-next 5/8] i40e: implement virtual device interface Jeff Kirsher
2013-06-14 3:55 ` [net-next 6/8] i40e: init code and hardware support Jeff Kirsher
2013-06-14 3:55 ` [net-next 7/8] i40e: sysfs and debugfs interfaces Jeff Kirsher
2013-06-14 3:55 ` [net-next 8/8] i40e: include i40e in kernel proper Jeff Kirsher
-- strict thread matches above, loose matches on Subject: below --
2013-09-06 5:43 [net-next 0/8][pull request] Intel Wired LAN Driver Updates Jeff Kirsher
2013-09-06 5:43 ` [net-next 1/8] i40e: main driver core Jeff Kirsher
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