Re: ARM imx.6 SATA speed regression

From: Dan MacDonald
Date: Wed Feb 08 2017 - 18:38:52 EST

Hi all

I'm still running the same 4.9.8 Arch kernel I was a few days ago and
I haven't done any updates but I decided to run hdparm again, a few
times actually, and now I'm getting 120/125 MB/s again on my SABRE
lite, as I was under 4.9.0.

When I last ran hdparm I ran it a few times and all the results were
all around 90 MB/s. I have no idea what caused those results to be so
far below the norm.

If I discover what the cause was I'll let you know but otherwise I'm
sorry about the noise!


On Wed, Feb 8, 2017 at 6:38 PM, Dan MacDonald <allcoms@xxxxxxxxx> wrote:
> Hi Gary
> I'll hopefully get to try some different kernels tonight or tomorrow
> night, otherwise it may have to wait until the weekend.
> As for bisecting and cross-compiling (which I won't have time to try
> again until this weekend), maybe not having cross-compilation working
> won't be such an obstacle provided I dont have to rebuild every kernel
> source file each time. I'm guessing I'll have to try approx 7 to 10
> kernel builds before the commit to blame is found, right? I've not
> built a kernel on my SABRE Lite yet but I recall building the generic
> armv7h kernel under Arch took approx 12 hours on my Banana Pi, which
> isn't that much slower than that the SL and has the same amount of RAM
> so at least the first build will take a smiliar amount of time.
> I'll update you all as soon as I have at least tried the various Arch
> kernel packages to narrow it down more.
> Thanks
> On Wed, Feb 8, 2017 at 5:48 PM, Gary Bisson
> <gary.bisson@xxxxxxxxxxxxxxxxxxx> wrote:
>> Hi Dan,
>> On Tue, Feb 07, 2017 at 05:02:40PM +0000, Dan MacDonald wrote:
>>> Thankfully there is an archive of older Arch ARM packages which should
>>> reduce the amount amount of bisection / compiling I may need to do and
>>> they have packages for most stable kernels between 4.9.0 and 4.9.8
>> How did that go?
>> I've tried 'hdparm -Tt' on several kernel version and couldn't confirm
>> your obervations:
>> 4.9.0:
>> Timing buffer-cache reads: 366 MB in 0.51 seconds = 733382 kB/s
>> Timing buffered disk reads: 221 MB in 3.00 seconds = 75411 kB/s
>> 4.9.8:
>> Timing buffer-cache reads: 358 MB in 0.51 seconds = 717720 kB/s
>> Timing buffered disk reads: 221 MB in 3.00 seconds = 75244 kB/s
>> 4.10-rc7:
>> Timing buffer-cache reads: 360 MB in 0.50 seconds = 723576 kB/s
>> Timing buffered disk reads: 244 MB in 3.00 seconds = 83024 kB/s
>> Are you sure rolling back to 4.9.0 improves the perf in your case?
>> Regards,
>> Gary