PCI express equipment

PCI express equipment

[kylin]

On one hand ,hardwarely,as it is always said, PCIE provides the
superexcellent performance

comparing with the PCI and PCI -X 
On the other ,softwarely,in most the application scenarios i have met
, the PCIE equipment will

have to use the pci-compatible driver first in linux.
because the Configuration head is pci compatible in the first 256 byte ,
it is allowed and really works. 
i know if we use the conventional Device Driver for pcie equipment,
the advanced option such as MSI ,Flow Control ,TC ,VC and hotplug are
unavailable, i also know

that the speed is mainly the problem of Bandwidth and Clocking. Still
i know that the Trafic

control mechanism is good for the arbitration and thus improve the
performance just like the

TCP protocol ways.
So my conclusion is :
the conventional Device driver will not be the bottle neck of the PCIE
performance as long as

only speed is concerned ,and the advanced options are only
Application-related.
here allow me just compare it with the network protocol ,
oh ,i just use the IP protocol ,with out the TCP /UDP way.
is that right ?or any wise can give some advice and  


-- 
we who r about to die,salute u!

Re: PCI express equipment

[Matthew Wilcox]

On Wed, May 04, 2005 at 07:51:12PM +0800, kylin wrote:
> On one hand ,hardwarely,as it is always said, PCIE provides the
> superexcellent performance
> 
> comparing with the PCI and PCI -X 
> On the other ,softwarely,in most the application scenarios i have met
> , the PCIE equipment will
> 
> have to use the pci-compatible driver first in linux.
> because the Configuration head is pci compatible in the first 256 byte ,
> it is allowed and really works. 
> i know if we use the conventional Device Driver for pcie equipment,
> the advanced option such as MSI ,Flow Control ,TC ,VC and hotplug are

rubbish.  MSI and Hotplug are independent of PCI Express and are used
by conventional PCI drivers today.  Flow control, TC and VC are all part
of the same thing.

> unavailable, i also know
> 
> that the speed is mainly the problem of Bandwidth and Clocking. Still
> i know that the Trafic
> 
> control mechanism is good for the arbitration and thus improve the
> performance just like the
> 
> TCP protocol ways.

Um, no, not really.  There's very little hardware support for VC/TC at the
moment, so having software support for it isn't a priority.  In addition,
it really depends how deep your PCI bus hierarchy is whether VC/TC will
have any effect on performance at all.

Why is this question on linux-scsi anyway?

-- 
"Next the statesmen will invent cheap lies, putting the blame upon 
the nation that is attacked, and every man will be glad of those
conscience-soothing falsities, and will diligently study them, and refuse
to examine any refutations of them; and thus he will by and by convince 
himself that the war is just, and will thank God for the better sleep 
he enjoys after this process of grotesque self-deception." -- Mark Twain

Re: PCI express equipment

[kylin]

On 5/4/05, Matthew Wilcox <matthew@wil.cx> wrote:
> On Wed, May 04, 2005 at 07:51:12PM +0800, kylin wrote:
> > On one hand ,hardwarely,as it is always said, PCIE provides the
> > superexcellent performance
> >
> > comparing with the PCI and PCI -X
> > On the other ,softwarely,in most the application scenarios i have met
> > , the PCIE equipment will
> >
> > have to use the pci-compatible driver first in linux.
> > because the Configuration head is pci compatible in the first 256 byte ,
> > it is allowed and really works.
> > i know if we use the conventional Device Driver for pcie equipment,
> > the advanced option such as MSI ,Flow Control ,TC ,VC and hotplug are
> 
> rubbish.  MSI and Hotplug are independent of PCI Express and are used
> by conventional PCI drivers today.  Flow control, TC and VC are all part
> of the same thing.
sorry for my innocence,but all i want to say here is if the unMSI and
unHotplug device driver would influence the normal speed in ONE 
common  scenarios
> > unavailable, i also know
> >
> > that the speed is mainly the problem of Bandwidth and Clocking. Still
> > i know that the Trafic
> >
> > control mechanism is good for the arbitration and thus improve the
> > performance just like the
> >
> > TCP protocol ways.
> 
> Um, no, not really.  There's very little hardware support for VC/TC at the
> moment, so having software support for it isn't a priority. 
yeah ,even the bios will rarely support this

> In addition,
> it really depends how deep your PCI bus hierarchy is whether VC/TC will
> have any effect on performance at all.
have you seen the E7520 chipset ,sir? 
> Why is this question on linux-scsi anyway?
because myu SCSI interface is connecting to the pcie bus:),love it and
love the dog :)

-- 
we who r about to die,salute u!