Hi Jeff, I recently added a Silicon Image 3512 based PCI card to an old Intel 440BX machine along with a single platter 500GB WD SATA2 drive. I'd have gone with an ahci sata2 controller but couldn't find one in 33MHz PCI. I compiled a new kernel, adding SCSI disk, libata and sata_sil support using make menuconfig and kernel.org sources installed the debian way on lenny 5.0.3. I left the old piix diver in so I could still boot from the old IDE disk and move the entire Linux system over. That all went pretty smoothly, I'm now booting from the new disk, and the sata subsystem is working pretty well, especially compared to the old 40GB Maxtor IDE disk (now removed from the system). However, I noticed that when running hdparm with O_DIRECT the transfer rate is ~85MB/s, while running buffered timings produces only ~55MB/s. This is an approximate 38% difference and I thought something might be amiss. On a much newer workstation with nvidia IDE chipset and 120GB Seagate IDE disk, running SLED10, O_DIRECT and buffered show identical numbers. I wouldn't think the kernel buffers in 2.6.31.1 would introduce that much overhead even on a much slower proc/mem subsystem, so I started digging around. Additionally, I've read on a number of Windows websites that this WD drive is averaging 100MB/s in various disk benchmarks and peaking at over 120MB/s. I have not tested my 3512/WD500 combo under Windows so I can't confirm those numbers. However, assuming they're valid, it seems my system is leaving quite a bit of performance on the table... I already knew from dmesg that the drive is being programmed at udma/100 even though the drive is capable of udma/133. Until yesterday I didn't realize that ncq was disabled (gasp). This drive is not in the blacklist in sata_sil.c or libata-core.c. I tried enabling ncq with echo 31 > /sys/block/sda/device/queue_depth but that gave a permissions error. I tried chmod +w on the above 'file' but then received "write error: Input/output error". So, I find myself stuck, not being a kernel hacker or even knowing the C language, seeing the code for the first time today, and wanting to change the behavior of my PCI card and disk. I'd like to bump up to udma/133 and enable ncq to at least test those modes, but don't quite know how to do this. I found sections in each of the c files above that are probably relevant but I have no clue what mods I need to make to effect the changes I want. I've searched the interwebs twice and found no solution, arriving at your doorstep. Please take pity on me, and provide me some basic english instructions on what to modify and where in order to enable udma6 and ncq. Or, better yet, if I could use boot arguments that would be great. I know how to do those, if given the proper arguments. I compile everything into my kernels, no driver modules and no initrd. Oh, and I still use LILO not grub. ;) I know that making these changes might possibly cause problems and/or data loss and I accept that responsibility. I _need_ to know if I'm leaving a bunch of performance on the table. After seeing winders benchmarks, I fear that I am. I'm having trouble sleeping not knowing the answer to this question. I'm obsessed with it now. :( Thanks in advance Jeff for any help you are able to provide. I copied the linux-ide list per your instructions in sata_sil.c. I am not subscribed to the list. If anyone else has the solution or tips to point me in the right direction, thank you all in advance as well. Sorry for my ramblings and if I posted too much information or back story. I've been in this computer game since '86 and it seems more information up front is usually better than not enough. -- Stan 00:11.0 RAID bus controller: Silicon Image, Inc. SiI 3512 [SATALink/SATARaid] Serial ATA Controller (rev 01) 00:00.0 Host bridge: Intel Corporation 440BX/ZX/DX - 82443BX/ZX/DX Host bridge (rev 03) 00:07.1 IDE interface: Intel Corporation 82371AB/EB/MB PIIX4 IDE (rev 01) SCSI subsystem initialized libata version 3.00 loaded sata_sil 0000:00:11.0: version 2.4 sata_sil 0000:00:11.0: PCI->APIC IRQ transform: INT A -> IRQ 19 scsi0 : sata_sil scsi1 : sata_sil ata1: SATA max UDMA/100 mmio m512@0xe9610000 tf 0xe9610080 irq 19 ata2: SATA max UDMA/100 mmio m512@0xe9610000 tf 0xe96100c0 irq 19 ata1: SATA link up 1.5 Gbps (SStatus 113 SControl 310) ata1.00: ATA-8: WDC WD5000AAKS-00V1A0, 05.01D05, max UDMA/133 ata1.00: 976773168 sectors, multi 16: LBA48 NCQ (depth 0/32) ata1.00: configured for UDMA/100 scsi 0:0:0:0: Direct-Access ATA WDC WD5000AAKS-0 05.0 PQ: 0 ANSI: 5 sd 0:0:0:0: [sda] 976773168 512-byte logical blocks: (500 GB/465 GiB) sd 0:0:0:0: [sda] Write Protect is off sd 0:0:0:0: [sda] Mode Sense: 00 3a 00 00 sd 0:0:0:0: [sda] Write cache: enabled, read cache: enabled, doesn't support DPO or FUA sda: sda1 sda2 sda3 < sda5 sda6 > sd 0:0:0:0: [sda] Attached SCSI disk ata2: SATA link down (SStatus 0 SControl 310) -- To unsubscribe from this list: send the line "unsubscribe linux-ide" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
