Hello, i have problems with extremely high IO wait times for some operations like apt-get-update and apt-get upgrade. Even checking the disks with hdparm shows this problem. I have not seen this problem with the I/O wait until recent kernels.
The system disk is rather slow: hdparm -t /dev/hda /dev/hda: Timing buffered disk reads: 26 MB in 3.23 seconds = 8.06 MB/sec Other disks are faster: hdparm -t /dev/hdb /dev/hdb: Timing buffered disk reads: 70 MB in 3.04 seconds = 23.05 MB/sec but do also show the extremely long wait times, up to 97% wait and only a few % CPU. The disks have DMA enabled and I have checked the memory for a long time with no problems. The problem can be related to the latency bug reported for recent kernels: "Large I/O operations result in slow performance and high iowait times", http://bugzilla.kernel.org/show_bug.cgi?id=12309 but running the provided programs ProcessSchedulerTest and ThreadSchedulerTest does not show the problems. I have tried three CPU schedulers: cfq (default), anticipatory and deadline with small differences. Kernels tried recently are 2.6.18-6-686, 2.6.25-2-682 and 2.6.26-1-686. Programs running consuming most of the memory are evolution and galeon. However, shutting them down does not change anything. dmesg does not show anything strange, except maybe: 1) Timer [ 0.154492] * Found PM-Timer Bug on the chipset. Due to workarounds for a bug, [ 0.154495] * this clock source is slow. Consider trying other clock sources 2) CPU [ 0.112943] weird, boot CPU (#0) not listed by the BIOS. [ 0.084928] CPU: L1 I cache: 16K, L1 D cache: 16K [ 0.084994] CPU: L2 cache: 256K [ 0.085036] Intel machine check architecture supported. [ 0.085079] Intel machine check reporting enabled on CPU#0. 3) HDD [ 2.804171] hda: IBM-DTTA-351010, ATA DISK drive [ 2.808019] Marking TSC unstable due to: TSC halts in idle. [ 3.142742] hda: host max PIO4 wanted PIO255(auto-tune) selected PIO4 [ 3.143077] hda: UDMA/33 mode selected [ 19.415943] hda: max request size: 128KiB [ 19.426396] hda: 19807200 sectors (10141 MB) w/466KiB Cache, CHS=19650/16/63 [ 19.426502] hda: cache flushes not supported [ 19.426629] hda: hda1 hda2 hda3 hda4 Comparing this with an old boot log for 2.6.14-1-686 shows: 1) Timer Using tsc for high-res timesource Real Time Clock Driver v1.12 2) CPU CPU: After generic identify, caps: 0383f9ff 00000000 00000000 00000000 00000000 00000000 00000000 CPU: After vendor identify, caps: 0383f9ff 00000000 00000000 00000000 00000000 00000000 00000000 CPU: L1 I cache: 16K, L1 D cache: 16K CPU: L2 cache: 256K CPU: After all inits, caps: 0383f9ff 00000000 00000000 00000040 00000000 00000000 00000000 Intel machine check architecture supported. Intel machine check reporting enabled on CPU#0. mtrr: v2.0 (20020519) CPU: Intel(R) Celeron(TM) CPU 1400MHz stepping 04 3) hda: IBM-DTTA-351010, ATA DISK drive hda: max request size: 128KiB hda: 19807200 sectors (10141 MB) w/466KiB Cache, CHS=19650/16/63, UDMA(33) hda: cache flushes not supported hda: hda1 hda2 hda3 hda4 For 2.6.26-2-686 we have cat /proc/mtrr reg00: base=0x00000000 ( 0MB), size= 256MB: write-back, count=1 reg01: base=0x10000000 ( 256MB), size= 128MB: write-back, count=1 reg02: base=0xe8000000 (3712MB), size= 64MB: write-combining, count=1 reg03: base=0xd8000000 (3456MB), size= 128MB: write-combining, count=2 and cat /proc/cpuinfo processor : 0 vendor_id : GenuineIntel cpu family : 6 model : 11 model name : Intel(R) Celeron(TM) CPU 1400MHz stepping : 4 cpu MHz : 1567.779 cache size : 256 KB fdiv_bug : no hlt_bug : no f00f_bug : no coma_bug : no fpu : yes fpu_exception : yes cpuid level : 2 wp : yes flags : fpu vme de pse tsc msr pae mce cx8 sep mtrr pge mca cmov pat pse36 mmx fxsr sse up bogomips : 3137.89 clflush size : 32 power management: Thank you for your help, Svante Signell -- To UNSUBSCRIBE, email to [email protected] with a subject of "unsubscribe". Trouble? Contact [email protected]
