Re: 2.6.12-rc6-mm1 & 2K lun testing

[Andrew Morton <akpm@osdl.org>]

Badari Pulavarty <pbadari@us.ibm.com> wrote:
>
> I sniff tested 2K lun support with 2.6.12-rc6-mm1 on
>  my AMD64 box. I had to tweak qlogic driver and
>  scsi_scan.c to see all the luns.
> 
>  (2.6.12-rc6 doesn't see all the LUNS due to max_lun
>  issue - which is fixed in scsi-git tree).
> 
>  Test 1:
>  	run dds on all 2048 "raw" devices - worked
>  great. No issues.
> 
>  Tests 2: 
>  	run "dds" on 2048 filesystems (one file
>  per filesystem). Kind of works. I was expecting better
>  responsiveness & stability.
> 
> 
>  Overall - Good news is, it works. 
> 
>  Not so good news - with filesystem tests, machine becomes 
>  unresponsive, lots of page allocation failures but machine 
>  stays up and completes the tests and recovers.

Any chance of getting a peek at /proc/slabinfo?

Presumably increasing /proc/sys/vm/min_free_kbytes will help.

We seem to be always ooming when allocating scsi command structures. 
Perhaps the block-level request structures are being allocated with
__GFP_WAIT, but it's a bit odd.  Which I/O scheduler?  If cfq, does
reducing /sys/block/*/queue/nr_requests help?

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