RE: core performance

[Wisam Jaddo <wisamm@nvidia.com>]

Hello Amit,

> -----Original Message-----
> From: amit sehas <cun23@yahoo.com>
> Sent: Monday, September 23, 2024 11:57 PM
> To: users@dpdk.org
> Subject: core performance
> 
> We are seeing different dpdk threads (launched via rte_eal_remote_launch()),
> demonstrate very different performance.
> 
> 
> 
> After placing counters all over the code, we realize that some threads are
> uniformly slow, in other words there is no application level issue that is
> throttling one thread over the other. We come to the conculsion that either
> the Cores on which they are running are not at the same frequency which
> seems doubtful or the threads are not getting a chance to execute on the cores
> uniformly.
> 
> 
> 
> It seems that isolcpus has been deprecated in recent versions of linux.
> 
> 
> 
> What is the recommended approach to prevent the kernel from utilizing some
> CPU threads, for anything other than the threads that are launched on them.

If you are wishing to run each thread on separate core, try to use rte_eal_mp_remote_launch()
instead of rte_eal_remote_launch(), make sure that your CPU is isolated, and you are passing correct
Cores that were isolated to your app using -c, -l.


> 
> 
> 
> Is there some API in dpdk which also helps us determine which CPU core the
> thread is pinned to?
> 
> I did not find any code in dpdk which actually performed pinning of a thread to
> a CPU core.
> 
> 
> 
> In our case it is more or less certain that the different threads are simply not
> getting the same CPU core time, as a result some are demonstrating higher
> throughput than the others ...
> 
> 
> 
> how do we fix this?

BRs,
Wisam Jaddo