Re: [Xen-ia64-devel] [PATCH][RFC][IA64] Accelerate IDE PIO on HVM/IA64

2006-12-04 Thread tgingold 
Quoting Kouya SHIMURA [EMAIL PROTECTED]:

 This patch significantly accelerates IDE PIO on HVM/IA64:
 * reduces the installation time of Windows 2003 Server
   from 10 hours(!) to 50min.
 * accelerates Windows CrashDumping speed from 40KB/sec
   (It takes over three hours for 512MB guest) to 850KB/sec.

 All reason for above slowness is the overhead of IDE PIO.
 Of course Windows should use DMA mode but we can't handle it.
 (FYI. Once installed, Windows usually uses DMA mode)

 On the other hand, x86 arch is rescued from this issue since it has a
 CISC instruction and multiple PIO requests can be processed in qemu-dm
 at one transaction. So this patch gives no benefit for x86.

 There are some dirty hacks in this patch:
 * To begin with, is it permissive to delegate the part of process of
 qemu-dm to hypervisor?
 * Currently it uses remnant of buffered_iopage (for VGA).
   Maybe I should prepare another page for IDE PIO.
 * May I use #ifdef __ia64__ ?
 * and so on.
Hi,

clever idea!

Two remarks:
* you can't assume page size = 16KB.  Xen can be compiled with other page
sizes (and should work with other page sizes).  As an easy approach, you can
disable this optimization iff page size != 16KB (or use smaller buffers).
* To be written data are not flushed directly.  I suppose they are flushed
while status is checked.  Is it safe ?

Tristan.

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RE: [Xen-ia64-devel] [PATCH][RFC][IA64] Accelerate IDE PIO on HVM/IA64

2006-12-04 Thread Zhang, Jingke 
Hi Kouya,
With your patch, win2k3 installation can be done within 40 minutes!
I have integrated #Cset12525 with the accelerating patch. 
It took 20 minutes to load file (you will see it in a blue screen).
And then the guest quickly installed the win2k3 from the CD-ROM, totally
within 40 minutes! 
What a wonderful patch! :)

Thanks,
Zhangjingke

-Original Message-
From: [EMAIL PROTECTED]
[mailto:[EMAIL PROTECTED] On Behalf Of Kouya
SHIMURA
Sent: Monday, December 04, 2006 10:28 AM
To: [EMAIL PROTECTED]; xen-ia64-devel@lists.xensource.com
Subject: [Xen-ia64-devel] [PATCH][RFC][IA64] Accelerate IDE PIO on
HVM/IA64

This patch significantly accelerates IDE PIO on HVM/IA64:
* reduces the installation time of Windows 2003 Server
  from 10 hours(!) to 50min.
* accelerates Windows CrashDumping speed from 40KB/sec
  (It takes over three hours for 512MB guest) to 850KB/sec.

All reason for above slowness is the overhead of IDE PIO.
Of course Windows should use DMA mode but we can't handle it.
(FYI. Once installed, Windows usually uses DMA mode)

On the other hand, x86 arch is rescued from this issue since it has a
CISC instruction and multiple PIO requests can be processed in qemu-dm
at one transaction. So this patch gives no benefit for x86.

There are some dirty hacks in this patch:
* To begin with, is it permissive to delegate the part of process of
qemu-dm to hypervisor?
* Currently it uses remnant of buffered_iopage (for VGA).
  Maybe I should prepare another page for IDE PIO.
* May I use #ifdef __ia64__ ?
* and so on.

Please show me the right way.

Thanks,
Kouya

Signed-off-by: Kouya Shimura [EMAIL PROTECTED]

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