Messages in this thread Patch in this message | | | Date | Wed, 29 Aug 2007 07:26:21 -0700 (PDT) | From | Martin Knoblauch <> | Subject | Re: Understanding I/O behaviour - next try |
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--- Jens Axboe <jens.axboe@oracle.com> wrote:
> On Tue, Aug 28 2007, Martin Knoblauch wrote: > > Keywords: I/O, bdi-v9, cfs > > > > Try limiting the queue depth on the cciss device, some of those are > notoriously bad at starving commands. Something like the below hack, > see > if it makes a difference (and please verify in dmesg that it prints > the > message about limiting depth!): > > diff --git a/drivers/block/cciss.c b/drivers/block/cciss.c > index 084358a..257e1c3 100644 > --- a/drivers/block/cciss.c > +++ b/drivers/block/cciss.c > @@ -2992,7 +2992,12 @@ static int cciss_pci_init(ctlr_info_t *c, > struct pci_dev *pdev) > if (board_id == products[i].board_id) { > c->product_name = products[i].product_name; > c->access = *(products[i].access); > +#if 0 > c->nr_cmds = products[i].nr_cmds; > +#else > + c->nr_cmds = 2; > + printk("cciss: limited max commands to 2\n"); > +#endif > break; > } > } > > -- > Jens Axboe > > > Hi Jens,
thanks for the suggestion. Unfortunatelly the non-direct [parallel] writes to the device got considreably slower. I guess the "6i" controller copes better with higher values.
Can nr_cmds be changed at runtime? Maybe there is a optimal setting.
[ 69.438851] SCSI subsystem initialized [ 69.442712] HP CISS Driver (v 3.6.14) [ 69.442871] ACPI: PCI Interrupt 0000:04:03.0[A] -> GSI 51 (level, low) -> IRQ 51 [ 69.442899] cciss: limited max commands to 2 (Smart Array 6i) [ 69.482370] cciss0: <0x46> at PCI 0000:04:03.0 IRQ 51 using DAC [ 69.494352] blocks= 426759840 block_size= 512 [ 69.498350] heads=255, sectors=32, cylinders=52299 [ 69.498352] [ 69.498509] blocks= 426759840 block_size= 512 [ 69.498602] heads=255, sectors=32, cylinders=52299 [ 69.498604] [ 69.498608] cciss/c0d0: p1 p2
Cheers Martin
------------------------------------------------------ Martin Knoblauch email: k n o b i AT knobisoft DOT de www: http://www.knobisoft.de - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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