Re: ARM imx.6 SATA speed regression

From: Dan MacDonald
Date: Wed Feb 08 2017 - 13:44:52 EST

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.


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