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SubjectRe: TR: SiI2112 + Seagate + nFroce2: no DMA!

Hi again,

Here's a more complete report on this issue.


Going to Fedora Core 12.4.22-1.2115.nptl fixed the DMA issue. The
Seagate SATA drive (ST3160023AS) came up in DMA mode.
The speed however (hdparm -t) was 25MB/s, better but still unacceptable.


I got the latest Fedora Core: 2.4.22-1.2149.nptl

Interestingly enough I found out that this release comes with a sata_sil
module that is not even in 2.4.24, it was probably ported from 2.6.1 by
the Fedora team.
Anyway I believe this is just a RAID driver, it did not change anything
(same as -1-).


Now I decided to live dangerously and I tried tuning max_kb_per_request,
the default being 15:

/echo "max_kb_per_request:128" > /proc/ide/hde/settings/

On my first hdparm -t I got 55MB/s !!!

BUT the drive was still making a lot of noise after I got the results,
and every time I tried the command again (only waiting a couple seconds
before retrying after I got the results), the throughput went lower each
time. In 5 retries I was at 7 MB/s. The drive was very noisy, still busy
minutes after I was done torturing him.

Unfortunately this did not come as a surprise as I had found the
following thread on Google:

> Andre Hedrick wrote:
> />/
> />Seagate and Silicon Image are the only two player (well intel now)
> who did/
> />their own PHY. They did not use the Marvel pairs./
> />/
> />It is a function of possible ECC on the wire and the relation to the/
> />segments in the PIO or SG operations. It is a FIFO issue based on
> 512byte/
> />boundaries being breached on corner cases./
> />/
> />The data on the wire is in 8K units./
> />/
> />It is a 7.5K + 0.5K corner case./
> />/
> />max_kb_per_request:15 == 7.5K/
> />/
> />This prevents this corner case until I can code the proper special
> case SG/
> />table./
> />/
> />drive->id->hwconfig |= 0x6000;/
> />/
> />Is needed to fake the driver for device side cable detect./
> />There are several issues and I have not had time to keep up./


The same machine is now dual boot with Windows 2000 SP4. I installed
Sandra 2004, a software for benchmnarking, and I got the following
results regarding the SATA drive:

Buffered Read: 83 MB/s
Sequential Read: 48 MB/s
Random Read: 8 MB/s
Buffered write: 68 MB/s
Sequential write: 48 MB/s
Random write: 9 MB/s

I know, comparing results obtained with 2 different benchmarking
products is almost irrelevant, but it is enough for the big picture:

There is nothing wrong with the harsware (Seagate or Silicon Image), it
works just fine with the windows drivers/libraries ... Oops did I just
praise microsoft?


I compiled/installed a new linux kernel to replace the one from the
Fedora distrib with 2.4.24

Absolutely no difference, same as -1-: 25 MB/s


Now I tried kernel 2.6.1: it is worse, it dropped to 14 MB/s !?!?!
I've seem several similar reports about 2.6.


So at this point I am ready to give up, and to simply buy a PATA drive.

However, after doing all the above (which is reported in chronological
order), I booted the latest Fedora Core: 2.4.22-1.2149.nptl again, and
decided to give another try to:

echo "max_kb_per_request:128" > /proc/ide/hde/settings

Now I have consistent 55 MB/s and no horrible noise from the drive, and
I let this run for 4 hours without any issue. Even typing the "hdparm
-Tt" commands one after another results are consistent.

What the heck is going on here (not that I don't appreciate things
working, but I'd like to understand)??? I can see only the following

- I was lucky, and it all depends on when you change
"max_kb_per_request" due to some race condition.
- going to 2.6.1, I upgraded 2 packages:
quota-tools: went from 3.06 to 3.10
procps: went from 2.0.17 to 3.1.15
I really don't see how this would change anything, but who knows...
- running the Win2000 benchmark with Sandra somehow did something to the
drive and/or the SATA controller, and they are now friends. Fishy...

Does anybody knows where the default 15kb is coming from for this drive?
How can I change this permanently? I mean other than than a hack rc
script running at init time...

I understand 2.6.1 is not using /proc/ide/hde/settings, how do I change
max_kb_per_request with this kernel?

Anyway I will make several more attempts with max_kb_per_request set to
128, to make sure it is really OK before enforcing it with a script
(anyway this script would have to be kernel-version specific, to keep a
back door).

Hope I haven't been too long and boring. Comments/suggestions are welcome.

Thanks for your help!


Emmanuel Hislen wrote:

> -----Message d'origine-----
> De : Emmanuel Hislen []
> Envoye : Saturday, January 24, 2004 1:27 AM
> A : Hugo Mills
> Cc :
> Objet : RE: SiI2112 + Seagate + nFroce2: no DMA!
> Hi Hugo,
> I have re-installed my machine with Fedora Core 1 (thinking a newer
> version
> than RH9 would make the jump to 2.4.24 or 2.6 easier), and this fixed the
> DMA issue :-)
> Now my SATA drive is running stable in UDMA6.
> However, performance is still way below expectations.
> I got a huge improvement: my disc read speed (hdparm -t) went from 1.3
> to 25
> MB/sec.
> This is still slower than my PATA drive on my 3 years old AMD 900 PC
> running
> Redhat 9.0 (around 35 MB/sec).
> Could you please let me know what you are getting so I know what to
> expect?
> My next step is to try 2.4.24 or 2.6.1 as you suggested, but googling
> around
> a little bit before I do so I found out a few worrying things:
> - people have reported a drop in performance on SATA in some 2.6 based
> kernel (2.6.0-test9), with reported speeds around 20MB/sec. Apparently
> there
> is no more way to tune max_kb_per_req in 2.6??
> - I have found reports that both ide and libdata libraries are limiting
> max_kb_per_req to 15 Kb specifically for Seagate drives. So It looks
> like I
> can't even set it to 128 (I did not even try as I saw reports of memory
> corruption).
> So basically since you've got it to work I'd like to know:
> * what speed you get, and what is the RPM of your Seagate
> * what is your max_kb_per_req setting (I have 15K)
> * what is your accoustic management setting (I have 0)
> I could not fix the time on linux so I am sending this mail from WinXP
> (just
> kidding I lost my mails on the linux machine after re-installing :-).
> Thanks,
> Emmanuel.
> -----Message d'origine-----
> De : Hugo Ranger Mills []De la part de Hugo
> Mills
> Envoye : Tuesday, January 20, 2004 12:58 AM
> A : manu
> Cc :
> Objet : Re: SiI2112 + Seagate + nFroce2: no DMA!
> On Tue, Dec 31, 2002 at 09:55:59PM -0800, manu wrote:
> Incidentally, did you know that the date on your computer is very,
> very wrong?
>> I'm about to give up on my SATA drive as I can't get it to work properly.
>> So I thought I may try asking the experts before falling back to PATA.
>> I have seen many mails reporting the same issue, some of them 6-month
>> old:
>> - SATA drive comes up in pio mode, not in dma
>> - trying to turn on dma with hdparm is a nightmare: I/O errors, crash
>> with data corruption... I tried both:
>> hddarm -d1 /dev/hde
>> and:
>> hdparm -u1 -c3 -d1 -X66 /dev/hde
>> crash in both cases :-((
>> Here's my equipment:
>> ABIT AN7 motherboard (nForce2 chipset, SiI3112 SATA controller)
>> AMD Athlon XP 2600+ (+ 512 DDR / 400 MHz)
>> SATA HD Seagate Barracuda 160 Gb
>> The SATA HD is my only drive. The only thing connected to my IDE
>> controllers is a DVD/CD combo.
>> Running Linux Redhat 9.0
>> kernel 2.4.20-28.9
> ^^^^^^^^^^^^^^^^^^
> This is your problem. There have been a number of bug-fixes to the
> SiI drivers since 2.4.20. Try it again with a newer kernel -- such as
> 2.4.24.
>> I've been googling for days now and could not come accross a solution,
>> on the contrary I came under the impression that the combination of
>> SiI3112 +and Seagate was doomed.
> Not so. I have a SiI3112 controller and a 120GiB Seagate drive, and
> they work very well together. I'm using 2.6.1, although 2.4.23 also
> worked well for me.
> [snip]
>> Isn't there a solution??
>> I am willing to try patches of experimental code. At this point I am
>> looking at reinstalling everything on a PATA drive anyway, so I have
>> nothing to loose.
> Try using 2.4.24 or 2.6.1.
> Hugo.
> --
> === Hugo Mills: hugo@... | | ===
> PGP key: 1C335860 from or
> --- All hope abandon, Ye who press Enter here. ---

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