Re: TCQ problems in 2.6.0-test1: the summary

[David Ford <david+powerix@blue-labs.org>]

 > > 4) Using a tcq-enabled kernel with queue depth of 8 results in

>>massive filesystem corruption for me, verified under reiserfs, and xfs.
>>Elevator choice does not appear to matter, while queue depth is
>>important - I do not appear to get filesystem corruption with queue
>>depth of 32. Reiser refuses to mount with such a kernel, and runs
>>--fix-fixable at boot time. This is reproducible every time.
>>    
>>
>
>This is really strange. The only difference between using 8 or 32 tags
>is when ide-disk stops attempting to queue. Are you getting any errors
>in dmesg when this happens? Reading the start io path for this, it looks
>correct to me. I'll have to try and reproduce when I get back.
>
On my laptop:

Here is the only thing that is similar on my system.  When TCQ is 
enabled, I have filesystem problems (minimal) every time I reboot and it 
nearly always affects the same files every time.  I too am using 
reiserfs.  I usually run reiserfsck and emerge the particular group of 
files.  For a while it was openssl libraries, now it's kde libraries.

Note, reiserfsck never indicates any problems were found or fixed but 
the problems are none-the-less fixed.  (reiser guys: reiserfsck 
--fix-fixable always results in "--fix-fixable ignored")

Also note that there is never any indication ever that something is 
wacky.  Just out of the blue a file or files are corrupt and the bootup 
result is the same every time.

(~) # hdparm -I /dev/hda |head -n10

/dev/hda:

ATA device, with non-removable media
        Model Number:       IC25N030ATCS04-0                       
        Serial Number:      CSL305DAGVK71A
        Firmware Revision:  CA3OA72A


On one of my servers:

TCQ fscks it up bad.  It ran for over a month on .73 with nary an issue 
then all of a sudden it started barfing within hours of boot complaining 
about:

Jul 19 10:55:31 james hdc: invalidating tag queue (0 commands)
Jul 19 10:55:41 james ide_tcq_intr_timeout: timeout waiting for 
completion interrupt

and further disk access causes D state.  I upgraded this machine to 
2.6.0-test1 and now it's having fits with apic or acpi but that's 
another email.  And a side note, if I have TCQ compiled in w/ 
2.6.0-test1, the kernel barfs a long 40+ function OOPS on bootup.  It's 
a 24/7 server so I haven't put a serial cable on it to capture the oops 
yet :/

(~) # hdparm -I /dev/hdc

/dev/hdc:

ATA device, with non-removable media
        Model Number:       IBM-DPTA-372050                        
        Serial Number:      JMYJMFZ1555
        Firmware Revision:  P76OA30A

more if desired.

Other than this, I don't see any filesystem issues.

david