John,
I think you misunderstood. Sandy Bridge ioatdma/dca should be supported in
kernel 3.4.41. However, I only see that "DCA" flag in ixgbe/dmesg when I am
using ixgbe 3.19.1, not when I am using 3.18.7. I am asking why that might
be. Nothing else changed, aside from rmmod ixgbe (3.18.7) and modprobe
ixgbe (3.19.1).
Alex,
There is nothing in dmesg to explain it. In fact, the igb driver always
uses DCA (prints "DCA enabled"), so I know that from a platform perspective
it is working.
To put it simply, I have two questions:
1. On Sandy bridge (and Ivy Bridge, etc), does DDIO replace DCA? If so,
what implication does the presence of "DCA" in enabled features on a
platform that is meant to have DDIO instead of DCA?
2. What change from 3.18.7 to 3.19.1 would cause the feature to become
Enabled on a platform that otherwise supports DCA?
Thanks,
Scott Silverman | IT | Simplex Investments | 312-360-2444
230 S. LaSalle St., Suite 4-100, Chicago, IL 60604
On Thu, Feb 13, 2014 at 1:59 PM, Alexander Duyck <
alexander.h.du...@intel.com> wrote:
> Scott,
>
> You might try checking the dmesg log on the systems that come up as not
> supporting DCA. There was a patch submitted a year or so ago that would
> disable DCA on platforms that had a misconfigured APIC ID tag map.
>
> It is possible that the platform might have had DCA disabled due to this
> in the case of the 3.18.7. You might want to go back and recheck the
> dmesg log to verify if DCA was disabled due to a configuration error in
> the BIOS.
>
> Thanks,
>
> Alex
>
> On 02/13/2014 08:27 AM, Scott Silverman wrote:
> > John,
> >
> > Thanks for the prompt response, but I still have some questions/concerns.
> >
> > -My motherboard (SuperMicro X9DRW) specifically provides a firmware
> option
> > to enable "DCA" but you state that the chipset doesn't include it at all?
> >
> > -Why is it reported only sometimes?
> >
> > Proc, Kern, ixgbe - DCA?
> > Sandy, 3.4, 3.18.7 - No DCA
> > Sandy, 3.4, 3.19.1 - DCA
> > Sandy, 3.12, 3.19.1 - DCA
> > Ivy, 3.12, 3.18.7 - DCA
> > Ivy, 3.12, 3.19.1 - DCA
> >
> >
> >
> >
> > Thanks,
> >
> > Scott Silverman | IT | Simplex Investments | 312-360-2444
> > 230 S. LaSalle St., Suite 4-100, Chicago, IL 60604
> >
> >
> > On Mon, Feb 10, 2014 at 4:26 PM, Ronciak, John <john.ronc...@intel.com
> >wrote:
> >
> >> The driver is just telling you what's possible not that DCA is enabled.
> >> The newer chipsets do not included it as it's all DDIO. So even though
> >> the NIC's is capable of support DCA the chipset does not have it so it
> >> won't be used. That's all this is saying. It's not an issue at all.
> >>
> >> Cheers,
> >> John
> >>
> >>
> >>> -----Original Message-----
> >>> From: Scott Silverman [mailto:ssilver...@simplexinvestments.com]
> >>> Sent: Monday, February 10, 2014 11:59 AM
> >>> To: e1000-devel@lists.sourceforge.net
> >>> Subject: [E1000-devel] DCA on Sandy Bridge?
> >>>
> >>> My understanding is the DDIO completely replaces DCA on sandy bridge
> >>> and newer hardware (E5+ xeons). I expected this is why I don't see
> >>> "DCA" listed when I load ixgbe, as I would on my nehalem systems.
> >>>
> >>> I see the following when loading ixgbe 3.18.7 on an E5-2670 system
> >>> (kernel
> >>> 3.4.41):
> >>>
> >>> ixgbe 0000:04:00.1: (PCI Express:5.0GT/s:Width x8) 00:1b:21:5c:66:0d
> >>> ixgbe 0000:04:00.1: eth3: MAC: 2, PHY: 9, SFP+: 4, PBA No: E68793-002
> >>> ixgbe 0000:04:00.1: eth3: Enabled Features: RxQ: 32 TxQ: 32 FdirHash
> >>> RSC ixgbe 0000:04:00.1: eth3: Intel(R) 10 Gigabit Network Connection
> >>>
> >>> If I take the same system, unload ixgbe, and load ixgbe 3.19.1, I see
> >>> this (emphasis mine):
> >>>
> >>> ixgbe 0000:04:00.1: PCI Express bandwidth of 32GT/s available ixgbe
> >>> 0000:04:00.1: (Speed:5.0GT/s, Width: x8, Encoding Loss:20%) ixgbe
> >>> 0000:04:00.1: eth3: MAC: 2, PHY: 9, SFP+: 4, PBA No: E68793-002 ixgbe
> >>> 0000:04:00.1: 00:1b:21:5c:66:0d ixgbe 0000:04:00.1: eth3: Enabled
> >>> Features: RxQ: 32 TxQ: 32 FdirHash *DCA*RSC ixgbe 0000:04:00.1: eth3:
> >>> Intel(R) 10 Gigabit Network Connection
> >>>
> >>> Can anyone explain why I see "DCA" with 3.19.1 and not with 3.18.7.
> >>> Also, does it matter?
> >>>
> >>> Thanks,
> >>>
> >>> Scott Silverman | IT | Simplex Investments | 312-360-2444
> >>> 230 S. LaSalle St., Suite 4-100, Chicago, IL 60604
> >>
> >
>
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