https://bugzilla.kernel.org/show_bug.cgi?id=70851 Bug ID: 70851 Summary: mpt3sas / LSI SAS 9300-8i write performance bottleneck Product: SCSI Drivers Version: 2.5 Kernel Version: 3.12.9-201.fc19.x86_64 Hardware: x86-64 OS: Linux Tree: Mainline Status: NEW Severity: high Priority: P1 Component: Other Assignee: scsi_drivers-other@xxxxxxxxxxxxxxxxxxxx Reporter: heinzm@xxxxxxxxxx Regression: No Description of problem: LSI SAS 9300-8i write performance too slow (whilst read performance is just fine). Version-Release number of selected component (if applicable): Kernel 3.12.9-201.fc19.x86_64 How reproducible: Always Steps to Reproduce: 1. attach 3 SSDs to adapter 2. create striped mapped device (e.g. using LVM) 3. dd of=/dev/$TheStripedDevice oflag=direct if=/dev/zero iflag=fullblock bs=2G count=1 Actual results: Single threaded read performance is as expected, ie. 3 SSDs (3 * Samsung 840EVO 1TB) with per drive sustained read throughput of 540MB/s lead to ~1.6GB/s on a striped logical volume (all 3 attached to one SFF-8643 port of the HBA via a 1:4 mSAS to SAS cable). Write performance on the same striped LV as in "Steps to Reproduce" (1 thread) maxes out at ~750MB/s as opposed to the maximum write throughput of ~490MB/s on each of the 3 SSDs written one by one Measured: - ~490MB/s writing (1 thread) to the individual SSDs one by one - ~750MB/s writing (1 thread) to all 3 SSDs in parallel via the striped LV - ~1GB/s (3 * ~340MB/s) writing (3 threads) to all 3 SSDs in parallel; ie. better than the striped LV write performance Expected results: Expecting >1.4GB/s write maximum on the striped LV written single threaded. -- You are receiving this mail because: You are watching the assignee of the bug. -- To unsubscribe from this list: send the line "unsubscribe linux-scsi" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
