Re: libata/sata_nv latency on NVIDIA CK804 [was Re: AMD64 X2 lost ticks on PM timer]

[Ingo Molnar <mingo@elte.hu>]

the patch below is a blind shot into the dark: it turns on MMIO for the 
sata_nv driver. But be careful with it - this turns on a probably 
totally untested mode in the driver and thus may damage your data. (It 
might not even work at all because the driver might not be ready for it 
- Jeff?).  I'd suggest to first boot into single-user mode with all 
filesystems readonly mounted.

on the low chance of this patch actually working, the interesting thing 
would be to check whether the latencies occur in MMIO mode too? (if they 
do then please send us the new latency traces too.)

	Ingo

---------

WARNING: this may damage your data. Be careful ...

 drivers/scsi/sata_nv.c |    1 +
 1 files changed, 1 insertion(+)

Index: linux/drivers/scsi/sata_nv.c
===================================================================
--- linux.orig/drivers/scsi/sata_nv.c
+++ linux/drivers/scsi/sata_nv.c
@@ -280,6 +280,7 @@ static struct ata_port_info nv_port_info
 	.host_flags	= ATA_FLAG_SATA |
 			  /* ATA_FLAG_SATA_RESET | */
 			  ATA_FLAG_SRST |
+			  ATA_FLAG_MMIO |
 			  ATA_FLAG_NO_LEGACY,
 	.pio_mask	= NV_PIO_MASK,
 	.mwdma_mask	= NV_MWDMA_MASK,