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    SubjectRe: [git patches] IDE update
    On 7/6/05, Bill Davidsen <davidsen@tmr.com> wrote:
    > Ondrej Zary wrote:
    > > Jens Axboe wrote:
    > >
    > >> On Tue, Jul 05 2005, Ondrej Zary wrote:
    > >>
    > >>> André Tomt wrote:
    > >>>
    > >>>> Al Boldi wrote:
    > >>>>
    > >>>>
    > >>>>> Bartlomiej Zolnierkiewicz wrote: {
    > >>>>>
    > >>>>>
    > >>>>>>>> On 7/4/05, Al Boldi <a1426z@gawab.com> wrote:
    > >>>>>>>> Hdparm -tT gives 38mb/s in 2.4.31
    > >>>>>>>> Cat /dev/hda > /dev/null gives 2% user 33% sys 65% idle
    > >>>>>>>>
    > >>>>>>>> Hdparm -tT gives 28mb/s in 2.6.12
    > >>>>>>>> Cat /dev/hda > /dev/null gives 2% user 25% sys 0% idle 73% IOWAIT
    > >>>>
    > >>>>
    > >>>>
    > >>>> The "hdparm doesn't get as high scores as in 2.4" is a old discussed
    > >>>> to death "problem" on LKML. So far nobody has been able to show it
    > >>>> affects anything but that pretty useless quasi-benchmark.
    > >>>>
    > >>>
    > >>> No, it's not a problem with hdparm. hdparm only shows that there is
    > >>> _really_ a problem:
    > >>>
    > >>> 2.6.12
    > >>> root@pentium:/home/rainbow# time dd if=/dev/hda of=/dev/null bs=512
    > >>> count=1048576
    > >>> 1048576+0 records in
    > >>> 1048576+0 records out
    > >>>
    > >>> real 0m32.339s
    > >>> user 0m1.500s
    > >>> sys 0m14.560s
    > >>>
    > >>> 2.4.26
    > >>> root@pentium:/home/rainbow# time dd if=/dev/hda of=/dev/null bs=512
    > >>> count=1048576
    > >>> 1048576+0 records in
    > >>> 1048576+0 records out
    > >>>
    > >>> real 0m23.858s
    > >>> user 0m1.750s
    > >>> sys 0m15.180s
    > >>
    > >>
    > >>
    > >> Perhaps some read-ahead bug. What happens if you use bs=128k for
    > >> instance?
    > >>
    > > Nothing - it's still the same.
    > >
    > > root@pentium:/home/rainbow# time dd if=/dev/hda of=/dev/null bs=128k
    > > count=4096
    > > 4096+0 records in
    > > 4096+0 records out
    > >
    > > real 0m32.832s
    > > user 0m0.040s
    > > sys 0m15.670s
    > >
    > Why is the system time so high? I tried that test here, and got:
    >
    > oddball:root> time dd if=/dev/hda of=/dev/null bs=128k count=4096
    > 4096+0 records in
    > 4096+0 records out
    >
    > real 0m37.927s
    > user 0m0.025s
    > sys 0m6.547s
    > oddball:root> uname -rn
    > oddball.prodigy.com 2.6.11ac7
    >
    > Now this is one of the slowest CPUs still in use (which I why I test
    > responsiveness on it), and it uses far less CPU time.
    > cat /proc/cpuinfo
    > processor : 0
    > vendor_id : GenuineIntel
    > cpu family : 6
    > model : 5
    > model name : Pentium II (Deschutes)
    > stepping : 1
    > cpu MHz : 348.507
    > cache size : 512 KB
    > fdiv_bug : no
    > hlt_bug : no
    > f00f_bug : no
    > coma_bug : no
    > fpu : yes
    > fpu_exception : yes
    > cpuid level : 2
    > wp : yes
    > flags : fpu vme de tsc msr pae mce cx8 apic sep mtrr pge mca
    > cmov pat pse36 mmx fxsr
    > bogomips : 686.08
    >
    >
    > The first post said it felt like running PIO, it certainly is using CPU
    > like it as well.
    >
    > Now here's some dmesg from this system...
    >
    > PIIX4: IDE controller at PCI slot 0000:00:07.1
    > PIIX4: chipset revision 1
    > PIIX4: not 100% native mode: will probe irqs later
    > ide0: BM-DMA at 0x1080-0x1087, BIOS settings: hda:DMA, hdb:pio
    > ide1: BM-DMA at 0x1088-0x108f, BIOS settings: hdc:DMA, hdd:pio
    > Probing IDE interface ide0...
    > hda: Maxtor 90845D4, ATA DISK drive
    > hdb: WDC AC31600H, ATA DISK drive
    > hdb: Disabling (U)DMA for WDC AC31600H (blacklisted)
    > ide0 at 0x1f0-0x1f7,0x3f6 on irq 14
    > Probing IDE interface ide1...
    > hdc: NEC CD-ROM DRIVE:28C, ATAPI CD/DVD-ROM drive
    > ide1 at 0x170-0x177,0x376 on irq 15
    > hda: max request size: 128KiB
    > hda: 16514064 sectors (8455 MB) w/512KiB Cache, CHS=16383/16/63, UDMA(33)
    > hda: cache flushes not supported
    > hda: hda1 hda2 hda3 hda4 < hda5 >
    > hdb: max request size: 128KiB
    > hdb: 3173184 sectors (1624 MB) w/128KiB Cache, CHS=3148/16/63
    > hdb: cache flushes not supported
    > hdb: hdb1 hdb2 hdb3
    > hdc: ATAPI 32X CD-ROM drive, 128kB Cache, UDMA(33)
    > Uniform CD-ROM driver Revision: 3.20
    >
    >
    > And indeed it does show hda as dma, and hdb as pio (older versions of
    > the kernel let me set hdb to dma and it worked fine...). But in the
    > posted demsg the BIOS settings show pio for hda. Is this in any way
    > relevant, given that UDA(33) appears later?

    BIOS setting is irrelevant and ~14MB/s for UDMA33 is OK.
    CPU cycles are wasted somewhere else...
    -
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