Red Hat Bugzilla – Bug 431312
2.6.24: After a random amount of time, SATA drive speed is reduced to 20MB/s
Last modified: 2008-02-08 19:15:35 EST
Description of problem: I have three SATA drives, a Raptor connected to Intel ICH8 and 2x WD Caviar drives connected to a JMicron 20360/20363. Kernels 2.6.22 and 2.6.23 are fine, however booting into 2.6.24 results in all SATA drive speeds being reduced to 20MB/s from the usal 65-80MB/s range I get with "hdparm -t /dev/sdX" What is weird about this problem is I discovered that the correct drivers are being used, and booting into single user mode and testing with hdparm does result in about 75MB/s on all drives. However, after a bit of disk activity (eg changing runlevels or starting X) the drive speed is suddenly reduced. Version-Release number of selected component (if applicable): kernel-2.6.24-9.fc9 How reproducible: Always Steps to Reproduce: 1. Boot in single user mode, hdparm -t /dev/sda 2. Boot in 3rd runlevel, hdparm -t /dev/sda 3. Boot in 5th runlevel, hdparm -t /dev/sda 4. Boot in single user mode and start service one by one, after each start run hdparm -t /dev/sda Actual results: Results from hdparm on each of the steps above: 1 --> 75MB/s 2 --> 20MB/s 3 --> 20MB/s 4 --> 75MB/s, however at one point the drives speed will drop to 20MB/s (it isn't a specific service, it will change each time a trial is run) Expected results: Drive speed isn't reduced to 20MB/s Additional info: I've attached logs from various kernels: * kernel-2.6.24-9.fc9.x86_64 (before drive speed was reduced) * kernel-2.6.24-9.fc9.x86_64 (after drive speed was reduced) * kernel-2.6.24-0.138.rc7.fc9.x86_64 * kernel-2.6.22.9-91.fc7.x86_64 The logs include dmesg, a timed run of dd reading a non-cached 4.6GB file, the `vmstat 1` output while the file was being copied and the hdparm -t tests on all three SATA drives.
Created attachment 293797 [details] Gzip'd test data
I saw the commit for 2.6.24.1 and rebuilt it locally, problem solved. $ sudo hdparm -t /dev/sda /dev/sdb /dev/sdc /dev/sda: Timing buffered disk reads: 192 MB in 3.01 seconds = 63.72 MB/sec /dev/sdb: Timing buffered disk reads: 184 MB in 3.03 seconds = 60.70 MB/sec /dev/sdc: Timing buffered disk reads: 224 MB in 3.01 seconds = 74.34 MB/sec