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
Attachment:
signature.asc
Description: PGP signature
- Follow-Ups:
- Re: htpt366 PCI latency value is really high
- From: Alan Cox <[email protected]>
- Re: htpt366 PCI latency value is really high
- References:
- htpt366 PCI latency value is really high
- From: Mike Mattie <[email protected]>
- Re: htpt366 PCI latency value is really high
- From: Sergei Shtylyov <[email protected]>
- htpt366 PCI latency value is really high
- Prev by Date: Re: Fw: [PATCH] ia64: race flushing icache in do_no_page path
- Next by Date: Re: [ext3][kernels >= 2.6.20.7 at least] KDE going comatose when FS is under heavy write load (massive starvation)
- Previous by thread: Re: htpt366 PCI latency value is really high
- Next by thread: Re: htpt366 PCI latency value is really high
- Index(es):
 |