http://bugzilla.kernel.org/show_bug.cgi?id=12752 Summary: megaraid-sas driver performance worse than on-board sata_nv Product: SCSI Drivers Version: 2.5 KernelVersion: vanilla 2.6.28.6 Platform: All OS/Version: Linux Tree: Mainline Status: NEW Severity: normal Priority: P1 Component: Other AssignedTo: scsi_drivers-other@xxxxxxxxxxxxxxxxxxxx ReportedBy: kernel-bugs.dev1world@xxxxxxxxxxxxxxx Latest working kernel version: Earliest failing kernel version: Distribution: Gentoo Hardware Environment: Dell PERC 5/i in a PCIe x16 slot, flashed with latest LSI firmware, nForce4, AMD 3800 X2. Software Environment: bonnie++ 1.94, HZ=300, NOHZ, CFQ, PREEMPT Problem Description: I ran two 1TB sata seagate drives on the on-board sata headers and created a software raid0 (of size 30GB). Ran bonnie++ using ext4 as my filesystem. Then, I put these on the PERC card and ran the same test with same FS and parameters. The results are shown below. Why is megaraid card slower than the on-board sata? With its 256MB cache (and enabled in BIOS), it should be doing better than on-board sata. Also, note the weird behavior of adaptive read. The rewrite improves but seq read b/w falls with adaptive read on the card. In both cases the speed is lower than the on-board sata. Version 1.94 ------Sequential Output------ --Sequential Input- --Random- Concurrency 1 -Per Chr- --Block-- -Rewrite- -Per Chr- --Block-- --Seeks-- Machine Size K/sec %CP K/sec %CP K/sec %CP K/sec %CP K/sec %CP /sec %CP OnBoardSATA 8G 398 99 229572 55 80200 19 1350 98 225241 32 321.8 9 ReadAhead 8G 487 99 182941 44 66079 13 2108 98 196957 26 360.4 7 ADaptiveReadAhed 8G 501 99 183013 44 78183 16 1566 91 163655 24 353.8 9 Latency 26057us 636ms 137ms 21486us 165ms 236ms Version 1.94 ------Sequential Create------ --------Random Create-------- sunil-amd-pc -Create-- --Read--- -Delete-- -Create-- --Read--- -Delete-- files /sec %CP /sec %CP /sec %CP /sec %CP /sec %CP /sec %CP 16 22084 54 +++++ +++ +++++ +++ +++++ +++ +++++ +++ +++++ +++ Latency 7642us 110us 956us 530us 295us 202us Both logical disks have the following cache related settings (reported by megacli): Default Cache Policy: WriteBack, ReadAdaptive, Cached, Write Cache OK if Bad BBU Current Cache Policy: WriteBack, ReadAdaptive, Cached, Write Cache OK if Bad BBU Access Policy: Read/Write Disk Cache Policy: Enabled I have tried various combos of these but the performance just tops out at what is shown above. Is there some sort of throttling going on in the driver under heavy load? Let me know if you need more info. Steps to reproduce: -- Configure bugmail: http://bugzilla.kernel.org/userprefs.cgi?tab=email ------- You are receiving this mail because: ------- You are the assignee for the bug, or are watching the assignee. -- 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
