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.
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"...
Cheers,
Mike Mattie - codermattie@xxxxxxxxx
WBR, Sergei
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