Latest working kernel version: unknown Earliest failing kernel version: 2.6.25-rc2 to latest git Distribution: GNU/Gentoo Linux Hardware Environment: P5W DH Deluxe, ahci (Intel ICH7R + Jmicron JMB363/361), Intel Core 2 Duo 6600, Software Environment: Problem Description: cfq has good interactivity during heavy load (esp. for desktop systems) but worse io-throughput compared to as, deadline, noop in general: (e.g. as, noop, deadline: 120 MB/s [platter speed], cfq: 55 MB/s) Steps to reproduce: use the kernel cat /sys/block/sda/queue/iosched/slice_idle 8 echo 1 >/proc/sys/vm/drop_caches dd if=/dev/sda of=/dev/null bs=64k count=5000 or hdparm -t /dev/sda should give bad throughput e.g. around 55-65 MB/s echo 0 >/sys/block/sda/queue/iosched/slice_idle echo 1 >/proc/sys/vm/drop_caches dd if=/dev/sda of=/dev/null bs=64k count=5000 should provide throughput around platter speed, e.g. 120 MB/s http://lkml.org/lkml/2008/5/10/71 http://lkml.org/lkml/2008/5/11/48
Created attachment 16192 [details] this is the output of blktrace from a vanilla-kernel (2.6.25) and with the patch mentioned below in "comment" correction for the latest kernel: 2.6.25-rc2 should be 2.6.26-rc2 (little typo) "vanilla" refers to 2.6.25 attached you'll find the output of a vanilla-run (sde, sdd) and a run with patch2 + vanilla - still no change (at least for me ;) ) + kernel-config and dmesg with some device-sensitive data cut out (printer) 01 == vanilla run 02 == run with patch2 03 == run of other harddisks [/dev/sda, /dev/sdc] (on vanilla-kernel + patch2) not encountering this problem (in fact never, even not in vanilla == no lowered throughput) ah, before I forget it (this might make a change): all hdd's run on ahci mode, all are not jumpered == 3 GB/s SATA-II/-I, not limited to 1.5 GB/s (shouldn't make a difference) /dev/sdd is on 4th port (?) of Intel ICH7R [ST3750330NS] /dev/sde is on Jmicron JMB363/JMB361 /dev/sdd + /dev/sde show this behavior (slowing down / bad throughput) * /dev/sda + /dev/sdc are on the ICH7R, too, but don't show this behavior (port 1 and 2 / 3 ?) * /dev/sda == /dev/sde --> both are of the same hdd model [ST3250620AS, Seagate] * /dev/sdc is [ST3250824AS] all 4 drives are S-ATA drives, the old atapi/ide-driver - whether it's compiled in or not - doesn't make a change (shouldn't) the p5w dh deluxe has some "strange" characteristics such as the ez-backup hardware raid-controller (which is currently disabled) enabling the combination of the jmicron and the ICH7R on a raid 5 & but shouldn't be the reason here for more information on this please consult the p5w dh deluxe handbook at asus.com the above mentioned patch is (should be) from: http://lkml.org/lkml/2008/5/14/97