> rate began falling and at 128k block-reads-at-a-time or larger, it drops > below > 20MB/s (again, only on buffered SATA). It's hard to imagine what would > slow down buffered SATA reads but not ATA and SCSI reads of the same > size. I'm using the 'cfq' scheduler with everything running at default
Try disabling NCQ - see if you've got a drive with the 'NCQ = no readahead' flaw. > priorities, but again, why only SATA slowness? It seems that at the driver > level, using direct reads, the SATA disk has the highest read rate (near > 80MB/s). Beats me - something is wrong that your setup triggers - could be firmware funnies or Linux ones. > The only way I could tell before was using hdparm to read the > parameters. > Since that doesn't work, it's hard to tell if they are set correctly, > but given hdparm supports identify to read modes on drives with libata. The one thing you cannot do is force modes right now. > More importantly, how does one set parameters for acoustic and power > saving parameters? Some of my disks are used as 'backup' devices for my hdparm or blktool > other computers. With the ATA disks, they were kept "spun down" when not > being used (only used, 'normally', in early AM hours). Well for backup devices you can use the fact SATA is hot/warm plug. > Another new "problem" (not as important) -- even though SATA disks are > called with "sdX", my ATA disks that *were* at hda-hdc are now at hde-hdg. NOTABUG - your BIOS has decided to move them from the legacy addresses so they move from hda-d to e-g. -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [EMAIL PROTECTED] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
