On Thu, 26 Apr 2007 18:30:33 +0400 Sergei Shtylyov <[EMAIL PROTECTED]> wrote:
> Hello.
>
> Mike Mattie wrote:
>
> > while hunting down some latency problems I found something quite
> > odd. The latency reported by lspci -v for the HTP203N card is
> > enormous.
>
> > 00:09.0 RAID bus controller: Triones Technologies, Inc. HPT302/302N
> > (rev 02) Subsystem: Triones Technologies, Inc. Unknown device 0001
> > Flags: bus master, 66MHz, medium devsel, latency 120, IRQ 17
> > I/O ports at ec00 [size=8]
> > I/O ports at e800 [size=4]
> > I/O ports at e400 [size=8]
> > I/O ports at e000 [size=4]
> > I/O ports at dc00 [size=256]
> > Expansion ROM at dffe0000 [disabled by cmd] [size=128K]
> > Capabilities: [60] Power Management version 2
>
> > I am assuming that the "latency" field here is the PCI latency timer
> > which means this card is a bus hog.
>
> > From some reading on this issue linux methodically sets a sane
> > value for all the PCI cards it sets up, which looks normal on the
> > rest of the system, which is set to the value: 32
>
> Hm, I'm only seeing clamping to the smallest of 64 and
> pcibios_max_latency (255) in arch/i386/pci/i386.c if the latency
> value is too low... Which arch are you using?
>
> > setting the value 32 with:
>
> > setpci -v -s "00:09.0" latency_timer=32
>
> > 00:09.0 RAID bus controller: Triones Technologies, Inc. HPT302/302N
> > (rev 02) Subsystem: Triones Technologies, Inc. Unknown device 0001
> > Flags: bus master, 66MHz, medium devsel, latency 48, IRQ 17
> > I/O ports at ec00 [size=8]
> > I/O ports at e800 [size=4]
> > I/O ports at e400 [size=8]
> > I/O ports at e000 [size=4]
> > I/O ports at dc00 [size=256]
> > Expansion ROM at dffe0000 [disabled by cmd] [size=128K]
> > Capabilities: [60] Power Management version 2
>
> > Results in 48, which is not what I asked, but hopefully this is
> > linux doing the right thing.
output is decimal, input is hex - self-rtfm.
> Not sure -- seems likely that it's the chip's own enforced minimum
> instead...
>
> > I know this chipset is pretty brain-damaged, but is this
> > high latency value a work-around for broken hardware, or
>
> More like it. Although HighPoint's own drivers force 64.
>
> > just a oversight ?
>
> Not likely since the value is too "special"...
I have ran with a setting of 40 for a couple of days without any trouble.
There are many reasons a card would default to a higher level, but in
the end it is basically tuning the card for a server application.
A warning that some cards default to high PCI latency values; settings that
can interfere with latency sensitive devices such as sounds cards - this
could be a help to others.
00:09.0 RAID bus controller: Triones Technologies, Inc. HPT302/302N
(rev 02) Subsystem: Triones Technologies, Inc. Unknown device 0001
Flags: bus master, 66MHz, medium devsel, latency 40, IRQ 19
I/O ports at ec00 [size=8]
I/O ports at e800 [size=4]
I/O ports at e400 [size=8]
I/O ports at e000 [size=4]
I/O ports at dc00 [size=256]
Expansion ROM at dffe0000 [disabled by cmd] [size=128K]
Capabilities: [60] Power Management version 2
> > Cheers,
> > Mike Mattie - [EMAIL PROTECTED]
>
> WBR, Sergei
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