Description of problem: The file iscsi-limits.h specifies a low number for ISCSI_CMDS_PER_LUN (currently 12). This will impact performance when IOs take longer to complete on a target (i.e. consider the case of random reads), and the initiator would benefit from increasing this beyond 12. Version-Release number of selected component (if applicable): 3.6.2-4 How reproducible: N/A Steps to Reproduce: N/A Actual results: Reduced performance with higher latency IO workloads (e.g. random IO) Expected results: Better performance with higher latency IO workloads (e.g. random IO) Additional info: Fix has already been checked into sourceforge 3-6 branch to increase IOs per LUN from 12 to 32. Since we're seeing lockups with RHEL3, U4 kernel (see bugzilla 145818), we probably need to tread more carefully here, as this has the potential to change the memory consumption characteristics of the iscsi driver, and potentially lead to more problems. Note that this is not a request to increase the can_queue value, so it might not be a big deal. However, it needs to be fully tested and not just put in there without much testing.
Hi Dave, this request is on my list for U5. I have already started testing it, and will continue, with an eye on the outcome of BZ 145818.
I decided not to make this change because it could make the problem in BZ 145818 worse. Once we have (at least a partial) workaround for BZ 145818, then we will increase the queue depth.
FYI - just had another internal (netapp) customer asking about this.
This bug is filed against RHEL 3, which is in maintenance phase. During the maintenance phase, only security errata and select mission critical bug fixes will be released for enterprise products. Since this bug does not meet that criteria, it is now being closed. For more information of the RHEL errata support policy, please visit: http://www.redhat.com/security/updates/errata/ If you feel this bug is indeed mission critical, please contact your support representative. You may be asked to provide detailed information on how this bug is affecting you.