i.MX6 and SATA performance

[GiuseppePagano]

Hi, does any one tested SATA support on i.MX6 platform ('I'm using a custom sabre lite board).

We have performance problem, just few minutes after boot sata disk halves troughput and we can't recover it any more. Seem not to be a power management problems, because performance slow down also in the middle of disk activity !

At start up performance are good:

root@linaro-ubuntu-desktop:~# hdparm -t /dev/sda

    Timing buffered disk reads: 188 MB in  3.01 seconds =  62.51 MB/sec
root@linaro-ubuntu-desktop:~# uptime
    ..... up 1 min,  ....

But after a while became worst:

root@linaro-ubuntu-desktop:~# hdparm -t /dev/sda
 Timing buffered disk reads:  88 MB in  3.03 seconds =  29.00 MB/sec
root@linaro-ubuntu-desktop:~# uptime
    ..... up 3 min,  ..

I also ask the same question on Bugs & Issues, sorry for the cross posting.

http://imxcommunity.org/forum/topics/i-mx6-sata-support-on-nitrogen6x?xg_source=activity

Regards

Giuseppe

[GiuseppePagano]

Hi Eric,

thanks for your test, and answer.

As I said mine result are good in the first minutes, I can repeat hdparm test 3 or 4 time,

and output is always: 63.22 MB/sec;

after a couple of minutes it became 28.15 MB/sec.

Since startup error counter is not null:

    # cat /sys/bus/scsi/devices/0\:0\:0\:0/ioerr_cnt
    0x3

That count remains always 3, also if I do a new reboot, or if I wait for performance degradation.

Bye

Giuseppe

[EricNelson]

I think we may need a faster hard drive to test against.

The one on my desk was scavenged from an old laptop and

is showing ~28 MB/second at boot time and after running for a while:

    ~$ hdparm -t /dev/sda
     /dev/sda:
     Timing buffered disk reads:   86 MB in  3.05 seconds =  28.18 MB/sec

Are you seeing any errors reported?

    ~$ cat /sys/bus/scsi/devices/0\:0\:0\:0/ioerr_cnt 0x0