UPGRADE YOUR BROWSER

We have detected your current browser version is not the latest one. Xilinx.com uses the latest web technologies to bring you the best online experience possible. Please upgrade to a Xilinx.com supported browser:Chrome, Firefox, Internet Explorer 11, Safari. Thank you!

cancel
Showing results for 
Search instead for 
Did you mean: 
Visitor orit
Visitor
416 Views
Registered: ‎07-08-2018

Axi crossbar outstanding

I’m quite new with the vivado IPI gui. I am using axi_corssbar in my design.

I created a 2X1 (2 slave 1 master)  axi crossbar IP and specified 8 outstanding read requests  ( as soon in the images below).

image.pngimage.pngimage.png

In simulation I see that my crossbar won’t acceptoutstanding requests, and that the arready signals wont raise until the previous requests rlast and rvalid is received, I see at the master side that the next agent  does not show any back pressure .... so I conclude that this behavior is related to the crossbar only. why the crossbar does not allow  outstanding request ?

image.png

 

This dramatically affect my performance, actually more than 2X drop !!!. what am I missing here ? why the crossbar does not respect the parameter specified at core generation step ? 

help !!!!

0 Kudos
3 Replies
Voyager
Voyager
355 Views
Registered: ‎02-01-2013

Re: Axi crossbar outstanding

Have you checked this?

2018-12-19_12-19-49.jpg

-Joe G.

Visitor orit
Visitor
337 Views
Registered: ‎07-08-2018

Re: Axi crossbar outstanding

Hi,

Thanks for the response.

To my understanding this is talking about how it decides the values for an AXI interconnect, while i am using the axi crossbar in which i define the parameters in the IP generator ( as seen in the images in the previous comment).

 

When deepening research in my problem is saw that my crossbar is in fact able to send 8 outstanding requests when i use the same ARID for all requests, but when using different ARID for each request ( as seen in the image in the previous comment) it doesn't allow any outstanding requests.

So i see that the parameters are received in my IP but the problem arises when using different ID's. Is there a limitation on the axi crossbar that enables us to use outstanding request's only when the ARID of the request's are the same?

 

Regards,

Ori

 

 

0 Kudos
Voyager
Voyager
329 Views
Registered: ‎02-01-2013

Re: Axi crossbar outstanding

ARM imposes restrictions on the ordering of reads handled by a slave, but those restrictions shouldn't be causing the behavior you're seeing now. 

Have you tried yet changing the Crossbar Optimization Strategy to "Maximize Performance"? Perhaps the performance of the crossbar implementation is 'skimpy' because it's still set to the default value of "Minimize Area".

-Joe G.