On Fri, 2012-07-06 at 15:30 -0500, Christoph Lameter wrote: > On Fri, 6 Jul 2012, James Bottomley wrote: > > > What people might pay attention to is evidence that there's a problem in > > 3.5-rc6 (without any OFED crap). If you're not going to bother > > investigating, it has to be in an environment they can reproduce (so > > ordinary hardware, not infiniband) otherwise it gets ignored as an > > esoteric hardware issue. > > The OFED stuff in the meantime is part of 3.5-rc6. Infiniband has been > supported for a long time and its a very important technology given the > problematic nature of ethernet at high network speeds. > > OFED crap exists for those running RHEL5/6. The new enterprise distros are > based on the 3.2 kernel which has pretty good Infiniband support > out of the box. > So I don't think the HCAs or Infiniband fabric was the limiting factor for small block random I/O in the RHEL 6.2 w/ OFED vs. Windows Server 2008 R2 w/ OFED setup mentioned earlier. I've seen both FC and iSCSI fabrics demonstrate the same type of random small block I/O performance anomalies with Linux/SCSI clients too. The v3.x Linux/SCSI clients are certainly better in the multi-lun per host small block random I/O case, but single LUN performance is (still) lacking compared to everything else. Also RHEL 6.2 does have the scsi-host-lock less bits in place now, but it's been more a matter of converting OFED ib_srp code to run in host-lock less mode to realize extra gains for multi-lun per host. -- To unsubscribe from this list: send the line "unsubscribe kvm" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
