System-drivers ported to Windows XP?

System-drivers ported to Windows XP?

[Uwaysi Bin Kareem]

Some may remember me as commenting on the excellent state of the  
linux-kernel, after I achieved 0.3ms reliable latency for audio-streams.

I have now decided to try and get as close as possible on Windows XP  
though. However some of the drivers on my windows XP install, is from  
2001. Windows update is ofcourse not giving me the available ones from  
2012, and they are hard to track down.

I was wondering if anyone had ported generic-system drivers, which then  
would probably be more optimized, than the 2001-ones, to windows XP?

If anyone wants to read about my findings on Windows XP, please read:  
http://paradoxuncreated.com/Blog/wordpress/?p=1506

Peace Be With You.

Re: System-drivers ported to Windows XP?

[Uwaysi Bin Kareem]

I have a list of drivers here, many of them dated 2001.  
http://paradoxuncreated.com/Blog/wordpress/?p=1608 (MS making me upset as  
usual.)
I am really just looking for better drivers, and thought maybe someone  
knew if more current opensource versions existed. I have not found  
anything online though, so therefore I ask here.

I have also thought about the ReactOS project, and wonder if they have  
more current drivers, seeing as they work on the project currently, I am  
discussing in their forum now, but communication is going slow.

Peace Be With You.

On Wed, 29 Aug 2012 00:50:31 +0200, jdow <jdow@earthlink.net> wrote:

> You might look into the ASIO drivers. Although for very heavy audio use
> 64 byte buffers are a more reliable than the ultra-short buffers you seem
> to be using. 100 channels with 7 ms latency through an audio matrix is
> a commercial product for XP and Win 7 for quite some time now. (Although
> Win 7 has some security policies that reduce performance gains that come
> through priority elevation somewhat.)
>
> SoundMan and Richmond are key words that will lead you to it via Google.
>
> {^_^}
>
> On 2012/08/28 12:01, Uwaysi Bin Kareem wrote:
>> Some may remember me as commenting on the excellent state of the  
>> linux-kernel,
>> after I achieved 0.3ms reliable latency for audio-streams.
>>
>> I have now decided to try and get as close as possible on Windows XP  
>> though.
>> However some of the drivers on my windows XP install, is from 2001.  
>> Windows
>> update is ofcourse not giving me the available ones from 2012, and they  
>> are hard
>> to track down.
>>
>> I was wondering if anyone had ported generic-system drivers, which then  
>> would
>> probably be more optimized, than the 2001-ones, to windows XP?
>>
>> If anyone wants to read about my findings on Windows XP, please read:
>> http://paradoxuncreated.com/Blog/wordpress/?p=1506
>>
>> Peace Be With You.
>> --
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Latency.

[Uwaysi Bin Kareem]

I have done some research on latency. I have config`d a linux kernel to  
run 0.3ms reliable latency with audiostreams, under normal worksituations.  
(An audioapp, and maybe some small tasks in between).

This also resulted in an extremely smooth gameplaying experience, like an  
asm-programmed custom hardware arcade. (Why gamebox-developers isn`t using  
this, is a mystery).

Recently I also tried to come as close to that experience on windows, and  
found that win32priorityseparation on 25, all processes on idle, to avoid  
cpu2 stalling cpu1, and minimal drivers, services, and processes gave a  
similar experience. Windows btw, also gives lower latency, if one moves  
windows, which one can use/abuse in a script/hack.

The feeling from low latency systems brings back the exhilaration of  
custom hardware and assembly programming. It gives a different feel, and I  
do believe it sets a high quality expectation to software and I wonder if  
that is why the Amiga is said to have so much good software, and  
responsible for it`s reputation.

My windows-partition now runs as good as an Amiga, and I managed to make  
it run even better, reminding me of singletasking systems like Mac OS.

Games are just so much more fun with this. And the overall os is so much  
more responsive.

More optimized stuff like Wayland will ofcourse even improve things more.

I do think that for "desktop" the focus should really be on low-latency  
systems.
If "desktop" and "server" are the two different profiles you usually  
config for in linux, how about two different standard configs? Or are  
these merging aswell, since I would think multi-cpu servers appreciate low  
os-jitter aswell?

Just some thoughts.

Peace Be With You.

Re: Latency.

[Uwaysi Bin Kareem]

There is a whole thread on phoronix, regarding this, where many people  
have similar sentiments.
Good to see others who understand the same. :)

http://phoronix.com/forums/showthread.php?71741-A-Low-Latency-Kernel-For-Linux-Gaming

Some people don`t seem to be noticing it. They are fewer in the thread  
though, but quite common.
Please also read my response to this:  
http://phoronix.com/forums/showthread.php?71741-A-Low-Latency-Kernel-For-Linux-Gaming&p=284229#post284229

Peace Be With You.

On Fri, 31 Aug 2012 00:50:28 +0200, Uwaysi Bin Kareem  
<uwaysi.bin.kareem@paradoxuncreated.com> wrote:

> I have done some research on latency. I have config`d a linux kernel to  
> run 0.3ms reliable latency with audiostreams, under normal  
> worksituations. (An audioapp, and maybe some small tasks in between).
>
> This also resulted in an extremely smooth gameplaying experience, like  
> an asm-programmed custom hardware arcade. (Why gamebox-developers isn`t  
> using this, is a mystery).
>
> Recently I also tried to come as close to that experience on windows,  
> and found that win32priorityseparation on 25, all processes on idle, to  
> avoid cpu2 stalling cpu1, and minimal drivers, services, and processes  
> gave a similar experience. Windows btw, also gives lower latency, if one  
> moves windows, which one can use/abuse in a script/hack.
>
> The feeling from low latency systems brings back the exhilaration of  
> custom hardware and assembly programming. It gives a different feel, and  
> I do believe it sets a high quality expectation to software and I wonder  
> if that is why the Amiga is said to have so much good software, and  
> responsible for it`s reputation.
>
> My windows-partition now runs as good as an Amiga, and I managed to make  
> it run even better, reminding me of singletasking systems like Mac OS.
>
> Games are just so much more fun with this. And the overall os is so much  
> more responsive.
>
> More optimized stuff like Wayland will ofcourse even improve things more.
>
> I do think that for "desktop" the focus should really be on low-latency  
> systems.
> If "desktop" and "server" are the two different profiles you usually  
> config for in linux, how about two different standard configs? Or are  
> these merging aswell, since I would think multi-cpu servers appreciate  
> low os-jitter aswell?
>
> Just some thoughts.
>
> Peace Be With You.

RE: latency

[David Laight]

From: Subhashini Rao Beerisetty <subhashbeerisetty@gmail.com>
> Sent: 03 December 2021 17:01
> 
>  [ Please keep me in CC as I'm not subscribed to the list]
> 
> Hi all,
> 
> We are using the Linux OS on an x86_64 machine. I need to measure the
> PCIe latency on my system, does kernel have any latency measurement
> module for the PCIe bus?

Slower than you expect :-)

Writes are asynchronous so really only limited by the actual speed
of the PCIe link and the rate the slave can process them.
So the actual latency of writes doesn't matter and the throughput
is reasonable.

Reads are much more problematic.
While the PCIe bus allows multiple outstanding read requests the
Intel x86 I've tested will only generate one outstanding request
for each cpu core.
So buffer reads are particularly slow.

The delays between on read completing and the next read TLP being
sent are (probably) negligible compared to the other delays.
So the latency of a read is just the time the two TLP take to
be transmitted over the wire (including delays for PCIe bridges)
plus the time the slave takes to generate the response TLP.
On the fpga slaves we are using that is (from memory) about 128
cycles of the 62.5MHz clock - ie absolutely ages.

For reads you definitely need to use the largest register size
possible - each read instruction (even misaligned ones) generates
exactly one read TLP.

If you are designing an interface for an fpga then consider using
writes from both sides for everything except bulk data.

You can (probably) measure the latency of your actual system using:
	x = rdtsc();
	v = readl();
	lfence;
	elapsed = rdtsc() - x;
However the TSC values depend on the current cpu frequency (which
will change 'randomly').
Or put the readl() into a loop and do enough that the high-res
system time delts makes sense.

	David

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