Re: [dpdk-users] Bigger mempool leads to worst performances.

["Benoit Ganne (bganne)" <bganne@cisco.com>]

> It looks like that in our environment increasing the mempool reduce the
> capture performance, any suggestion on what I might look at to
> troubleshoot the problem? Apparently we can't go beyond 4GiB mempool
> without performance penalties.
> (Please note that 1GiB hugepage are configured to serve all the require
> additional memory.)

I'd bet it on page walks because of TLB misses: if I am not mistaken, on Intel you only have 4 TLB entries for 1GB hugepages, and prior to Skylake you have no victim cache. So, as soon as you use more than 4 x 1GB hugepages, you'll start triggering page walks because all your pages do no longer fit in the TLB.
You should be able to check that with 'perf stat -e dTLB-loads,dTLB-load-misses,dTLB-stores,dTLB-store-misses -a -I1000' or similar.

Best
ben