IDE drives

IDE drives

[David Becker]

I'm seeing quite slow IDE write performance on Xenolinux-1.2 
Native linux writes at 30MB/s to an ext2 fs, and Xenolinux DOM0 gets
about 2MB/s (this is not a virtual disk extent).   hdparm doesn't work
under xenolinux, but that is only part of the problem.  Native linux
writes at 6MB/s without any hdparm tuning.

The SCSI hosts seem fine.  native linux writes to scsi at 36MB/s and
xen at 28MB/s.

Is the IDE speed about what I should expect for xen-1.2 or did I screw
up my configuration?





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Re: IDE drives

[Ian Pratt]

> 
> I'm seeing quite slow IDE write performance on Xenolinux-1.2 
> Native linux writes at 30MB/s to an ext2 fs, and Xenolinux DOM0 gets
> about 2MB/s (this is not a virtual disk extent).   hdparm doesn't work
> under xenolinux, but that is only part of the problem.  Native linux
> writes at 6MB/s without any hdparm tuning.

Take a look at the boot messages -- I suspect Xen hasn't got a
proper driver for your IDE chipset and is falling back to PIO.

You could try porting the driver from Linux (which I expect will
be easy), or wait until the new IO stuff is ready.
 
> The SCSI hosts seem fine.  native linux writes to scsi at 36MB/s and
> xen at 28MB/s.

I'm surprised you're seeing such a drop. With our aacraid
PERC3/Di cards we see (MB/s):
xenolinux	Write 28.3	Read 46.7
linux		Write 29.2	Read 47.2

Are you sure you're using the same part of the disk? It could be
a driver version issue, but I find it surprising you're
seeing such a performance drop.


Cheers,
Ian


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Re: IDE drives

[David Becker]

" Take a look at the boot messages -- I suspect Xen hasn't got a
" proper driver for your IDE chipset and is falling back to PIO.

Yep, you are right.  Xenolinux says PIO.  I'll add this chipset to my todo list.

    ide: Assuming 33MHz system bus speed for PIO modes; override with idebus=xx
    ServerWorks CSB5: IDE controller on PCI bus 00 dev 79
    ServerWorks CSB5: detected chipset, but driver not compiled in!
    ServerWorks CSB5: chipset revision 147
    ServerWorks CSB5: not 100% native mode: will probe irqs later
        ide0: BM-DMA at 0x0700-0x0707, BIOS settings: hda:DMA, hdb:DMA
        ide1: BM-DMA at 0x0708-0x070f, BIOS settings: hdc:DMA, hdd:DMA
    hda: ST340016A, ATA DISK drive
    hdc: LG CD-ROM CRN-8245B, ATAPI CD/DVD-ROM drive
    ide0 at 0x1f0-0x1f7,0x3f6 on irq 14
    ide1 at 0x170-0x177,0x376 on irq 15
    hdc: ATAPI 24X CD-ROM drive, 128kB Cache
    Uniform CD-ROM driver Revision: 3.12
    hda: 78156288 sectors (40016 MB) w/2048KiB Cache, CHS=4865/255/63 PIO (slow!)


" Are you sure you're using the same part of the disk?

most likely not.  I ran the scsi writes on two different hosts just as a
sanity check, and not as a rigorous check.  Both were the same hardware
and may even have had other users on them.  It was close enough to be labeled
'the same' for my purposes.


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RE: IDE drives

[Neugebauer, Rolf]

This seems quiet slow.

Can you check the xen boot message for a warning if PIO is used? That
might explain. I think there was something on the xen-devel list a while
back. There might be two mentioning of PIO (or at least I think that
used to be the case) one of them might be wrong. 

Rolf


> -----Original Message-----
> From: xen-devel-admin@lists.sourceforge.net [mailto:xen-devel-
> admin@lists.sourceforge.net] On Behalf Of David Becker
> Sent: 24 March 2004 14:34
> To: xen-devel@lists.sourceforge.net
> Subject: [Xen-devel] IDE drives
> 
> 
> I'm seeing quite slow IDE write performance on Xenolinux-1.2
> Native linux writes at 30MB/s to an ext2 fs, and Xenolinux DOM0 gets
> about 2MB/s (this is not a virtual disk extent).   hdparm doesn't work
> under xenolinux, but that is only part of the problem.  Native linux
> writes at 6MB/s without any hdparm tuning.
> 
> The SCSI hosts seem fine.  native linux writes to scsi at 36MB/s and
> xen at 28MB/s.
> 
> Is the IDE speed about what I should expect for xen-1.2 or did I screw
> up my configuration?
> 
> 
> 
> 
> 
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> This SF.Net email is sponsored by: IBM Linux Tutorials
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> _______________________________________________
> Xen-devel mailing list
> Xen-devel@lists.sourceforge.net
> https://lists.sourceforge.net/lists/listinfo/xen-devel



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