On Tue, Mar 14, 2006 at 07:43:41AM -0800, Roland Dreier wrote: > Vu> I don't have a good test to measure performance; however, I > Vu> ran multiple dd streams on raw devices (no filesystem or > Vu> buffer cache involved) to measure the impact of using > Vu> FMRs. With Mellanox srp target referenced implementation SW + > Vu> 14 SATA drives + PCI-E lion cub, I hit 850 MB/s with FMRs and > Vu> 710 MB/s without it. > > Hmm, I'm not sure whether dd is a good test.
dd is not since dd doesn't validate the result of read or write. Try "spew". For "raw" performance, I prefer "sgp_dd" for maximising throughput to "normal" SCSI disks: [EMAIL PROTECTED]:~$ dpkg -S sgp_dd sg3-utils: /usr/bin/sgp_dd > I'd be more interested to know if typical filesystem I/O generates > requests that are mergeable via FMRs. How would we know if FMRs are merging transactions? (more on this below) > Vu> Do you have a good test to measure performance? > > No, I don't. That's why I ask. spew gives some perf metrics. Also see iozone, bonnie++, and diskbench. > Yes, I need to do that, and also add some instrumentation to see how > often FMRs are used on different workloads. ah ok. I was hoping HW (HCA) could tell us. Keeping stats can cost substantial performance because of additional cacheline activity (read/modify/write operations). I ripped out the "interesting" (to me only) stats in my IOMMU code for this reason. grant _______________________________________________ openib-general mailing list [email protected] http://openib.org/mailman/listinfo/openib-general To unsubscribe, please visit http://openib.org/mailman/listinfo/openib-general
