Re: SATA kernel-buffered read VERY slow (not raid, Promise TX300 card); 2.6.23.1(vanilla)

[Linda Walsh <lkml@tlinx.org>]

Robert Hancock wrote:
> Linda Walsh wrote:
>> Alan Cox wrote:
>>>> rate began falling; at 128k block-reads-at-a-time or larger, it 
>>>> drops below
>>>> 20MB/s (only on buffered SATA).
>>> Try disabling NCQ - see if you've got a drive with the 'NCQ = no
>>> readahead' flaw.
> http://linux-ata.org/faq.html#ncq
---
    When drive initializes, dmesg says it has NCQ (depth 0/32)
    Reading the queue_depth under /sys, shows a queuedepth of "1".

But more importantly -- I notice a chronic error message associate
with this drive that may be causing some or all of the problem:
---
Jan  2 20:06:10 Ishtar kernel: ata1.00: exception Emask 0x0 SAct 0x0 
SErr 0x0 action 0x2
Jan  2 20:06:10 Ishtar kernel: ata1.00: port_status 0x20080000
Jan  2 20:06:10 Ishtar kernel: ata1.00: cmd 
c8/00:10:30:06:03/00:00:00:00:00/e0 tag 0 cdb 0x0 data 8192 in
Jan  2 20:06:10 Ishtar kernel:          res 
50/00:00:3f:06:03/00:00:00:00:00/e0 Emask 0x2 (HSM violation)
Jan  2 20:06:13 Ishtar kernel: ata1: limiting SATA link speed to 1.5 Gbps
Jan  2 20:06:13 Ishtar kernel: ata1.00: exception Emask 0x0 SAct 0x0 
SErr 0x0 action 0x6
Jan  2 20:06:13 Ishtar kernel: ata1.00: port_status 0x20080000
Jan  2 20:06:13 Ishtar kernel: ata1.00: cmd 
c8/00:10:00:8b:04/00:00:00:00:00/e0 tag 0 cdb 0x0 data 8192 in
Jan  2 20:06:13 Ishtar kernel:          res 
50/00:00:0f:8b:04/00:00:00:00:00/e0 Emask 0x2 (HSM violation)
Jan  2 20:06:14 Ishtar kernel: ata1: exception Emask 0x10 SAct 0x0 SErr 
0x0 action 0x3
Jan  2 20:06:14 Ishtar kernel: ata1: hotplug_status 0x80
Jan  2 20:06:15 Ishtar kernel: ata1: exception Emask 0x10 SAct 0x0 SErr 
0x0 action 0x3
Jan  2 20:06:15 Ishtar kernel: ata1: hotplug_status 0x80
---
What da heck?  Note, this is with NCQ-queuing set to "1".  Only 
reference I could find for this error referred to "older drives", but 
this is a
2007-model year drive with ATA-7 and udma-6.

> I don't think you can get or get the multi count currently, it just 
> uses the best supported value.
ok
>
>> 2) Drive Advanced Power Management setting("-B") (write-only):
>> "HDIO_DRIVE_CMD failed: Input/output error"
>> 3) Drive Acoustic ("-M"), read = " acoustic      = not supported",
>> write = " HDIO_DRIVE_CMD:ACOUSTIC failed: Input/output error"
>
> Not sure about these ones.. Does anything show up in dmesg when you do 
> this?
---
    Yes:
    (for "-B", power-management)
ata1.00: exception Emask 0x0 SAct 0x0 SErr 0x0 action 0x0
ata1.00: port_status 0x20200000
ata1.00: cmd ef/05:fe:00:00:00/00:00:00:00:00/40 tag 0 cdb 0x0 data 0
         res 51/04:fe:00:00:00/00:00:00:00:00/40 Emask 0x1 (device error)
ata1.00: configured for UDMA/133
ata1: EH complete
sd 1:0:0:0: [sdb] 1465149168 512-byte hardware sectors (750156 MB)
sd 1:0:0:0: [sdb] Write Protect is off
sd 1:0:0:0: [sdb] Mode Sense: 00 3a 00 00
sd 1:0:0:0: [sdb] Write cache: enabled, read cache: enabled, doesn't 
support DPO or FUA
----
   (for "-M" acoustic management):
ata1.00: exception Emask 0x0 SAct 0x0 SErr 0x0 action 0x0
ata1.00: port_status 0x20200000
ata1.00: cmd ef/42:fe:00:00:00/00:00:00:00:00/40 tag 0 cdb 0x0 data 0
         res 51/04:fe:00:00:00/00:00:00:00:00/40 Emask 0x1 (device error)
ata1.00: configured for UDMA/133
ata1: EH complete
sd 1:0:0:0: [sdb] 1465149168 512-byte hardware sectors (750156 MB)
sd 1:0:0:0: [sdb] Write Protect is off
sd 1:0:0:0: [sdb] Mode Sense: 00 3a 00 00
sd 1:0:0:0: [sdb] Write cache: enabled, read cache: enabled, doesn't 
support DPO or FUA