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Re: HEADS-UP: SATA NCQ support merged (from jdolecek-ncq branch)

I see you are on a ThinkPad as well. I have mentioned it elsewhere, on my ThinkPad T61p I am getting reliably since the NCQ update the following:
wd0 at atabus0 drive 0
wd0: <Hitachi HTS725032A9A364>
wd0: drive supports 16-sector PIO transfers, LBA48 addressing
wd0: 298 GB, 620181 cyl, 16 head, 63 sec, 512 bytes/sect x 625142448 sectors
piixide0:0:0: bad state 0 in wdc_ata_bio_intr
panic: wdc_ata_bio_intr: bad state
fatal breakpoint trap in supervisor mode
trap type 1 code 0 rip 0xffffffff8021c0c5 cs 0x8 rflags 0x246 cr2 0 ilevel 0x8 rsp 0xffffe40040003c38
curlwp 0xffffe4013bb27840 pid 0.2 lowest kstack 0xffffe400400002c0

The disk is on the place of the CD with an appropriate tray, this happens with kernels from releng, not only with mine. There is another disk, an SSD in the internal bay, with a Windows 10 and some Linux installation, the default boot is NetBSD from the tray.

Chavdar Ivanov

On Wed, 11 Oct 2017 at 20:57 Michael van Elst <> wrote: (Thor Lancelot Simon) writes:

>It probably has to do with our small maximum transfer size.  The disk is
>probably trying to be safer and *not* caching tagged writes as aggressively,
>but with only 32 commands in-flight (SCSI/SAS allow 256) and a maximum
>transfer size of 64K (our MAXPHYS), that's only 2MB of in-flight data;
>maybe not enough to keep up with the actual bandwidth of the media at
>its real latency.

With a larger MAXPHYS there wouldn't be as many transfers in flight.

The disk here in the Thinkpad behaves differently. With up to 5 concurrent
transfers (320k buffer size for dd reading the raw partition) everything
is fine. With 6 concurrent transfers the speed goes down again, with
30 transfers we are at half speed.

                                Michael van Elst
                                "A potential Snark may lurk in every tree."

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