On 6/1/2011 2:21 PM, Alan Cox wrote:

quoted

Thanks, Asai!  I don't think cfq is the ideal I/O scheduler to be
testing.  Could you run again with deadline and/or noop and see how that
changes your throughput and perf report?  Also, just for completeness,
could you tell us which kernel you ran this against?

kernel 2.6.38.6

How many processors is this system, just looking at the lock contention
which is pretty horrible.

8 processors (2 quad-core CPUs)
Intel(R) Xeon(R) CPU           X5672  @ 3.20GHz

I'd been expecting various red flags in the AHCI/libata/scsi queue code
but it seems at first glance that the block queue stuff is killing us and
the scsi/ata code is a distraction (unless of course its causing a lot of
the lock time)

No-op would be most interesting but the I/O scheduler numbers don't look
pretty.

Alan

On looking into the data in below links, lock and block queue are 
consuming more time when running with ahci driver. Correct me if I 
missing something.

With mtipx2xx, the driver is spot on processing I/O. Any idea of who is 
the top offender when running with mtipx2xx?

Filename                  |    Description
-------------------------------------------------------------------------------------------
perf_report_ahci_cfq      : perf call graph for ahci driver with cfq
                             scheduler enabled
http://www.micron.com/get-document/?documentId=6768

vdbench.ahci.cfq.html     : vdbench summary of a run for ahci driver
                             with cfq scheduler enabled
http://www.micron.com/get-document/?documentId=6774

perf_report_ahci_deadline : perf call graph for ahci driver with
                             deadline scheduler enabled
http://www.micron.com/get-document/?documentId=6769

vdbench_ahci.deadline.html: vdbench summary of a run for ahci driver
                             with deadline scheduler enabled
http://www.micron.com/get-document/?documentId=6775

perf_report_ahci_noop     : perf call graph for ahci driver with noop
                             scheduler enabled
http://www.micron.com/get-document/?documentId=6770

vdbench_ahci.noop.html    : vdbench summary of a run for ahci driver
                             with noop scheduler enabled
http://www.micron.com/get-document/?documentId=6776

perf_report_micron        : perf call graph for Micron block driver
                             (mtipx2xx)
http://www.micron.com/get-document/?documentId=6772

vdbench_micron.html       : vdbench summary of a run for Micron block
                             driver (mtipx2xx)
http://www.micron.com/get-document/?documentId=6777

This is the first time we are hosting files for public access, that 
process took time to get to here.