>>>>> "Al" == Al Boldi <[email protected]> writes:
Al> Jens Axboe wrote:
>> On Wed, Sep 13 2006, Al Boldi wrote:
>> > Jens Axboe wrote:
>> > > This lists the main features of the 'block' branch, which is bound for
>> > > Linus when 2.6.19 opens:
>> > >
>> > > - Splitting of request->flags into two parts:
>> > > - cmd type
>> > > - modified flags
>> > > Right now it's a bit of a mess, splitting this up invites a cleaner
>> > > usage and also enables us to implement generic "messages" passed on
>> > > the regular queue for the device.
>> > >
>> > > - Abstract out the request back merging and put it into the core io
>> > > scheduler layer. Cleans up all the io schedulers, and noop gets
>> > > merging for "free".
>> > >
>> > > - Abstract out the rbtree sorting. Gets rid of duplicated code in
>> > > as/cfq/deadline.
>> > >
>> > > - General shrinkage of the request structure.
>> > >
>> > > - Killing dynamic rq private structures in deadline/as/cfq. This
>> > > should speed up the io path somewhat, as we avoid allocating several
>> > > structures (struct request + scheduler private request) for each io
>> > > request.
>> > >
>> > > - meta data io logging for blktrace.
>> > >
>> > > - CFQ improvements.
>> > >
>> > > - Make the block layer configurable through Kconfig (David Howells).
>> > >
>> > > - Lots of cleanups.
>> >
>> > Does it also address the strange "max_sectors_kb<>192 causes a
>> > 50%-slowdown" problem?
>>
>> (remember to cc me/others when replying, I can easily miss lkml
>> messages for several days otherwise).
>>
>> It does not, the investigation of that is still pending I'm afraid. The
>> data is really puzzling, I'm inclined to think it's drive related. Are
>> you reproducing it just one box/drive, or on several?
Al> Several boxes, same drive.
Al> /dev/hda:
Al> ATA device, with non-removable media
Al> Model Number: WDC WD1200JB-00DUA0
Al> Serial Number: WD-WMACM1007651
Al> Firmware Revision: 65.13G65
Al> Standards:
Al> Supported: 6 5 4 3
Al> Likely used: 6
I've got a pair of drives which are very close in model type, and I
can run some non-destructive tests on them if you like to confirm
what's going on here if you like:
/dev/hde:
ATA device, with non-removable media
Model Number: WDC WD1200JB-00CRA1
Serial Number: WD-WMA8C4365875
Firmware Revision: 17.07W17
Standards:
Supported: 5 4 3
Likely used: 6
jfsnew:~> sudo hdparm -I /dev/hdg | head
/dev/hdg:
ATA device, with non-removable media
Model Number: WDC WD1200JB-00EVA0
Serial Number: WD-WMAEK2844058
Firmware Revision: 15.05R15
Standards:
Supported: 6 5 4
Likely used: 6
The drives have different defaul max_sectors too:
> cat /sys/block/hdg/queue/max_sectors_kb
512
> cat /sys/block/hde/queue/max_sectors_kb
128
Let me know your test method and I'll run it here and post the
results.
John
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