On Tue, Apr 06, 2021 at 10:37:38AM +0800, Honggang LI wrote: > On Mon, Apr 05, 2021 at 08:23:54AM +0300, Leon Romanovsky wrote: > > From: Leon Romanovsky <leonro@xxxxxxxxxx> > > > > From Avihai, > > > > Relaxed Ordering is a PCIe mechanism that relaxes the strict ordering > > imposed on PCI transactions, and thus, can improve performance. > > > > Until now, relaxed ordering could be set only by user space applications > > for user MRs. The following patch series enables relaxed ordering for the > > kernel ULPs as well. Relaxed ordering is an optional capability, and as > > such, it is ignored by vendors that don't support it. > > > > The following test results show the performance improvement achieved > > Did you test this patchset with CPU does not support relaxed ordering? I don't think so, the CPUs that don't support RO are Intel's fourth/fifth-generation and they are not interesting from performance point of view. > > We observed significantly performance degradation when run perftest with > relaxed ordering enabled over old CPU. > > https://github.com/linux-rdma/perftest/issues/116 The perftest is slightly different, but you pointed to the valid point. We forgot to call pcie_relaxed_ordering_enabled() before setting RO bit and arguably this was needed to be done in perftest too. Thanks > > thanks >
