Re: USB Storage speed regression since 2.6.12

["linux-os \(Dick Johnson\)" <linux-os@analogic.com>]

On Thu, 1 Sep 2005, DervishD wrote:

>    Hi all :)
>
>    I don't know if this is a known issue, but usb-storage speed for
> 'Full speed' devices dropped from 2.6.11.12 (more than 800Kb/s) to
> 2.6.12 (less than 250Kb/s). The problem still exists in 2.6.13.
>
>    The lack of speed seems to affect only the OHCI driver. My test
> was done over a PCI USB 2.0 card, ALi chipset, OHCI driver (well
> EHCI+OHCI) and using a full speed device capable of 12MBps. The
> average measured speeds are:
>
>    - 2.4.31:           about 450Kb/seg
>    - 2.6.11-Debian:    about 800Kb/seg
>    - 2.6.11.12:        about 820Kb/seg
>    - 2.6.12.x:         about 200Kb/seg
>    - 2.6.13:           about 200Kb/seg
>
>    The .config is more or less the same in all kernels. I've took a
> look at the ChangeLog for 2.6.12 and there are lots of changes in the
> USB subsystem but I cannot identify which one could be the culprit.
>
>    If anyone needs more information (for example, device
> identification in all kernels) just tell. I don't provide much more
> information since this can be a known issue and so there is no need
> to pollute the list with a long .config and dmesg output...
>
>    Thanks in advance :)
>
>    Raúl Núñez de Arenas Coronado
>
> --
> Linux Registered User 88736 | http://www.dervishd.net
> http://www.pleyades.net & http://www.gotesdelluna.net
> It's my PC and I'll cry if I want to...
> -

The SCSI subsystem has similar problems. The speed has
gone down since linux-2.4.26. I'm compiling a bunch of
kernels to see which one starts the down-hill trend.
The SCSI disc sybsystem with this kernel (the initial RedHat
distribution, unmodified 2.6.5-1.358) is awful.

The data I have so far from `hdparam -tT` is:

linux-2.6.13

/dev/sda:
  Timing buffer-cache reads:   3036 MB in  2.00 seconds = 1515.96 MB/sec
  Timing buffered disk reads:   28 MB in  3.14 seconds =   8.93 MB/sec

/dev/sdb:
  Timing buffer-cache reads:   3052 MB in  2.00 seconds = 1523.95 MB/sec
  Timing buffered disk reads:   78 MB in  3.01 seconds =  25.87 MB/sec

/dev/sdc:
  Timing buffer-cache reads:   3024 MB in  2.00 seconds = 1511.47 MB/sec
  Timing buffered disk reads:   56 MB in  3.11 seconds =  18.01 MB/sec

/dev/hda:
  Timing buffer-cache reads:   3040 MB in  2.00 seconds = 1520.23 MB/sec
  Timing buffered disk reads:  132 MB in  3.02 seconds =  43.66 MB/sec

linux-2.4.26	(baseline)

/dev/sda:
  Timing buffer-cache reads:   3032 MB in  2.00 seconds = 1589.64 MB/sec
  Timing buffered disk reads:  128 MB in  3.12 seconds =  43.02 MB/sec

/dev/sdb:
  Timing buffer-cache reads:   3062 MB in  2.00 seconds = 1605.36 MB/sec
  Timing buffered disk reads:  166 MB in  3.01 seconds =  58.73 MB/sec

/dev/sdc:
  Timing buffer-cache reads:   3024 MB in  2.00 seconds = 1511.47 MB/sec
  Timing buffered disk reads:  102 MB in  3.08 seconds =  34.72 MB/sec

/dev/hda:
  Timing buffer-cache reads:   3032 MB in  2.00 seconds = 1589.64 MB/sec
  Timing buffered disk reads:  130 MB in  3.01 seconds =  45.28 MB/sec

Linux-2.4.26 had reasonable performance. The latest kernel has
essentially the same IDE performance, but absolutely awful SCSI
performance, sort of like a floppy.

IT looks as though the SCSI system isn't brought into
synchronous mode because there are two slow devices
(urelated) on the NARROW interface even though there
are 3 WIDE FAST devices on the other bus.

SCSI subsystem initialized
ACPI: PCI Interrupt 0000:02:00.0[A] -> GSI 21 (level, low) -> IRQ 17
scsi0 : Adaptec AIC7XXX EISA/VLB/PCI SCSI HBA DRIVER, Rev 6.2.36
         <Adaptec 2940 Ultra SCSI adapter>
         aic7880: Ultra Wide Channel A, SCSI Id=7, 16/253 SCBs

   Vendor: SEAGATE   Model: ST32171W          Rev: 0484
   Type:   Direct-Access                      ANSI SCSI revision: 02
  target0:0:0: asynchronous.
scsi0:A:0:0: Tagged Queuing enabled.  Depth 4
  target0:0:0: Beginning Domain Validation
  target0:0:0: wide asynchronous.
  target0:0:0: Domain Validation skipping write tests
  target0:0:0: FAST-20 WIDE SCSI 40.0 MB/s ST (50 ns, offset 8)
  target0:0:0: Ending Domain Validation
SCSI device sda: 4194057 512-byte hdwr sectors (2147 MB)
SCSI device sda: drive cache: write back
SCSI device sda: 4194057 512-byte hdwr sectors (2147 MB)
SCSI device sda: drive cache: write back
  sda: sda1 sda2 < sda5 >
Attached scsi disk sda at scsi0, channel 0, id 0, lun 0
   Vendor: SEAGATE   Model: ST318233LWV       Rev: 0002
   Type:   Direct-Access                      ANSI SCSI revision: 03
  target0:0:1: asynchronous.
scsi0:A:1:0: Tagged Queuing enabled.  Depth 4
  target0:0:1: Beginning Domain Validation
  target0:0:1: wide asynchronous.
  target0:0:1: FAST-20 WIDE SCSI 40.0 MB/s ST (50 ns, offset 8)
  target0:0:1: Ending Domain Validation
SCSI device sdb: 35566480 512-byte hdwr sectors (18210 MB)
SCSI device sdb: drive cache: write back
SCSI device sdb: 35566480 512-byte hdwr sectors (18210 MB)
SCSI device sdb: drive cache: write back
  sdb: sdb1 sdb2
Attached scsi disk sdb at scsi0, channel 0, id 1, lun 0
   Vendor: SEAGATE   Model: ST39102LW         Rev: 0005
   Type:   Direct-Access                      ANSI SCSI revision: 02
  target0:0:2: asynchronous.
scsi0:A:2:0: Tagged Queuing enabled.  Depth 4
  target0:0:2: Beginning Domain Validation
  target0:0:2: wide asynchronous.
  target0:0:2: Domain Validation skipping write tests
  target0:0:2: FAST-20 WIDE SCSI 40.0 MB/s ST (50 ns, offset 8)
  target0:0:2: Ending Domain Validation
SCSI device sdc: 17783240 512-byte hdwr sectors (9105 MB)
SCSI device sdc: drive cache: write back
SCSI device sdc: 17783240 512-byte hdwr sectors (9105 MB)
SCSI device sdc: drive cache: write back
  sdc: sdc1 sdc2 sdc3
Attached scsi disk sdc at scsi0, channel 0, id 2, lun 0
   Vendor: YAMAHA    Model: CRW6416S          Rev: 1.0b
   Type:   CD-ROM                             ANSI SCSI revision: 02
  target0:0:4: asynchronous.
  target0:0:4: Beginning Domain Validation
  target0:0:4: Domain Validation skipping write tests
  target0:0:4: FAST-10 SCSI 10.0 MB/s ST (100 ns, offset 15)
  target0:0:4: Ending Domain Validation
libata version 1.12 loaded.


Cheers,
Dick Johnson
Penguin : Linux version 2.6.5-1.358 on an i686 machine (5537.79 BogoMips).
Warning : 98.36% of all statistics are fiction.

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