Re: Strange vmstat output. 2.6.10 Scheduler?

["Catalin(ux aka Dino) BOIE" <util@deuroconsult.ro>]

> On Tue, Feb 01 2005, Catalin(ux aka Dino) BOIE wrote:
>> Hello!
>>
>> I have a weird problem with a server. I use deadline.
>> The output of vmstat is:
>>  1  1  12312   6064   7580 815432    0    0  5332   456 1263  3119 22  5  0
>>  73
>>  0  1  12312   5280   7584 816240    0    0  6204   620 1307  1530 15  4  0
>>  81
>>  0  1  12312   6096   7528 815088    0    0  7604  8732 1256  1398  5  8  0
>>  87
>>  0  1  12312   6048   7528 815144    0    0     8     8 1243  1440 14  2  0
>>  84
>>  0  1  12312   6048   7528 815168    0    0     0     0 1261  1287  8  2  0
>>  90
>>  0  2  12312   6040   7584 815184    0    0     0     0 1258  1197  7  2  0
>>  91
>>  0  2  12312   6024   7584 815208    0    0     0     0 1265  1309  6  5  0
>>  89
>>  0  2  12312   6024   7584 815208    0    0     0   136 1253   365  2  2  0
>>  96
>>  0  2  12312   5984   7584 815208    0    0     0     0 1268   413  2  1  0
>>  97
>>  0  2  12312   6052   7584 815208    0    0     0     0 1270   375  2  1  0
>>  97
>>  1  0  12312   6164   7584 815156    0    0  6188   288 1270  4314 23  5  0
>>  72
>>  0  1  12312   5684   7536 815592    0    0  4128  8656 1270  1316 14  3  0
>>  83
>>  0  1  12312   5684   7536 815608    0    0     0     0 1258  1251  8  3  0
>>  89
>>  0  1  12312   5552   7536 815628    0    0     0     0 1258  1327  8  2  0
>>  90
>>  0  1  12312   5552   7536 815644    0    0     0     0 1264  1127  7  2  0
>>  91
>>  0  1  12312   5552   7536 815668    0    0     0     2 1258  1225  8  3  0
>>  89
>>  0  3  12312   5248   7588 816108    0    0  4340   585 1249  1316  7  3  0
>>  90
>>  0  2  12312   5612   7584 815680    0    0  3092   188 1254   411  3  1  0
>>  96
>>  0  2  12312   5564   7584 815676    0    0     0     0 1261   259  2  2  0
>>  96
>>  0  2  12312   5564   7584 815676    0    0     0     0 1254   348  2  1  0
>>  97
>>
>> It seems strange because iowait is at 90% but nothing is trasnfered
>> to/from disk. Why is that?
>
> The bi/bo numbers are sometimes a little confusing, it doesn't mean that
> the drive is actually doing 8656kb of io at that very second - only that
> this much io was queued to the drive.
>
>> I run postgresql on this server and I'm not satistied by it's speed.
>>
>> Single Pentium IV, IDE disk.
>>
>> What can be the problem?
>
> Do you have write cache enabled on the drive?

No. Intentionaly I disabled it:

ATA device, with non-removable media
         Model Number:       WDC WD800JB-00CRA1
         Serial Number:      WD-WMA8E8797395
         Firmware Revision:  17.07W17
Standards:
         Supported: 5 4 3 2
         Likely used: 6
Configuration:
         Logical         max     current
         cylinders       16383   16383
         heads           16      16
         sectors/track   63      63
         --
         CHS current addressable sectors:   16514064
         LBA    user addressable sectors:  156301488
         device size with M = 1024*1024:       76319 MBytes
         device size with M = 1000*1000:       80026 MBytes (80 GB)
Capabilities:
         LBA, IORDY(can be disabled)
         bytes avail on r/w long: 40     Queue depth: 1
         Standby timer values: spec'd by Standard, with device specific 
minimum
         R/W multiple sector transfer: Max = 16  Current = 16
         Recommended acoustic management value: 128, current value: 254
         DMA: mdma0 mdma1 mdma2 udma0 udma1 udma2 udma3 udma4 *udma5
              Cycle time: min=120ns recommended=120ns
         PIO: pio0 pio1 pio2 pio3 pio4
              Cycle time: no flow control=120ns  IORDY flow control=120ns
Commands/features:
         Enabled Supported:
            *    READ BUFFER cmd
            *    WRITE BUFFER cmd
            *    Host Protected Area feature set
            *    Look-ahead
                 Write cache
            *    Power Management feature set
                 Security Mode feature set
            *    SMART feature set
            *    Device Configuration Overlay feature set
                 Automatic Acoustic Management feature set
                 SET MAX security extension
            *    DOWNLOAD MICROCODE cmd
            *    SMART self-test
            *    SMART error logging
Security:
                 supported
         not     enabled
         not     locked
                 frozen
         not     expired: security count
         not     supported: enhanced erase
HW reset results:
         CBLID- above Vih
         Device num = 0 determined by CSEL
Checksum: correct

Thanks!
>
> -- 
> Jens Axboe
>

---
Catalin(ux aka Dino) BOIE
catab at deuroconsult.ro
http://kernel.umbrella.ro/