John Stoffel wrote:
> >>>>> "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.
Thanks for your input!
Are you running UDMA5? Can you dump the full hdparm -I
What thruput do you get with cat /dev/hd[eg] > /dev/null?
What does cat /sys/block/hde/queue/read_ahead_kb say?
Then try this for best performance:
echo 192 > /sys/block/hde/queue/max_sectors_kb
echo 192 > /sys/block/hde/queue/read_ahead_kb
and repeat the thruput test reporting vmstat results.
Thanks!
--
Al
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