Re: [Freedos-user] FreeDOS is slow in Raspberry 4

[Rugxulo]

Hi,

On Fri, Mar 20, 2020 at 4:03 PM Swap Jim via Freedos-user
 wrote:
>
> Tried it. Didn't change anything. But thanks for the suggestion.

I don't think debug info is loaded into RAM at all. I'm not sure if
even DJGPP does that either. So don't worry about that (much).

I don't think "-O3" is reliable. In fact, you could go crazy trying a
million different options. (Try asking Gentoo users on IRC, maybe
somebody will help.)

I have never used any R-Pi machines, but I would naively suggest "-s
-O2 -finline-functions -fomit-frame-pointer -mtune=native".

But, honestly, QEMU is just slow. It's okay for simple stuff, but you
really suffer on more complex things. Not complaining! Anything is
better than bugs (or no compatibility at all!). Hardware VT-X (KVM)
helps a ton. Not sure what ARM supports for that.

Well, you could (weakly) try my MetaDOS floppy image. (I may need to
update it, yet again, one of these weeks.) It's fairly simple and
doesn't need any major installing. So simple networking should work
okay via packet driver. It has various tests you could try, just to
see how long it takes to complete. It's far from perfect, though. Try
doing some simple compilations: "tests /t oberon" or "tests /t
turpas32" or "tests /t nasm98dj" or "tests /t invaders".

* 
https://www.ibiblio.org/pub/micro/pc-stuff/freedos/files/distributions/unofficial/metados/


> On 2020-03-19 05:48, Louis Santillan wrote:
> >
> > `-g` [0] adds debugging info which will make the QEMU binary larger,
> > and produce code & data to allow instrumenting and debugging at
> > runtime.  This will blow cache performance since more code & data
> > overflow the cache.  I recommend removing this all together.
> >
> > I recommend trying `-O3` or `-Ofast` without `-g` and 
> > retesting/rebenchmarking.


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Re: [Freedos-user] FreeDOS is slow in Raspberry 4

[Swap Jim via Freedos-user]

Tried it. Didn't change anything. But thanks for the suggestion.

On 2020-03-19 05:48, Louis Santillan wrote:

Something to note in the original bug report is that CFLAGS chosen are
not optimal for performance (`make 'CFLAGS=-Wall -g -O2 -w'`).
Specifically, the `-g` and `-O2`  flags should probably be changed.

`-g` [0] adds debugging info which will make the QEMU binary larger,
and produce code & data to allow instrumenting and debugging at
runtime.  This will blow cache performance since more code & data
overflow the cache.  I recommend removing this all together.

`-O2` [1] instructs the compiler to enable all performance options
that do not involve a space-time tradeoff.  Generally `-O3` is
considered to produce the most "optimal" code, `-Os` is beneficial for
CPUs with small caches and `-Ofast` can enable further performance
potentially at the cost of program execution correctness.

I recommend trying `-O3` or `-Ofast` without `-g` and retesting/rebenchmarking.


[0] https://gcc.gnu.org/onlinedocs/gcc/Debugging-Options.html
[1] https://gcc.gnu.org/onlinedocs/gcc/Optimize-Options.html#Optimize-Options

On Wed, Mar 18, 2020 at 1:48 PM Jim Hall  wrote:




On Wed, Mar 18, 2020 at 3:00 PM Eric Auer  wrote:



Hi Ralf,


How about first installing to a directory or diskimage stored
in a ramdisk on the host OS, then copying that to mass storage?



This would be a bit like the old chicken and egg problem. The time you
would spend to copy the contents of the FreeDOS distro from the SD card
to a RAM disk on the RPi is likely not much faster...


I expect it to be much faster because: You only read from the
slow SD card and you read fewer, larger files. The bad parts,
writing many small files, would be on the fast ramdisk side.
Also, you can start from a FreeDOS ISO on the SD card, which
again is only one big file to copy from the web to the card.
When done, you copy one big file, the diskimage, once from
the ramdisk to the SD card :-)
[..]



Someone had suggested that option to me - install FreeDOS to a HD image in a 
RAM drive, then copy the HD image back to storage.

But I didn't want to explain those extra steps in my article. And really, installing FreeDOS on 
QEMU+RPi takes longer, but it's not "all day" long. It's more like "start the 
install, and make a cup of coffee while the install finishes." For a one-time thing, it's not 
too bad.


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Re: [Freedos-user] FreeDOS is slow in Raspberry 4

[Ralf Quint]

On 3/19/2020 7:59 AM, David McMackins wrote:

It's worth noting that Raspbian is still only distributed in 32-bit
form, failing to take full advantage of the 64-bit ARM processor on the
Pi 4. If some other distribution is built for arm64, that may well
perform better than Raspbian even though it is the best "supported" OS.

The 32-bit distribution was a conscious decision by the Raspberry Pi
Foundation to maintain binary compatibility with older Pi boards so that
newcomers would not be confused about which download to choose.

I don't know how much of an effect running in 32-bit mode has on the
performance of the newer CPU, but I thought it was worth mentioning as a
possible reason why an unofficial distribution might run better on a Pi 4.

I doubt that there is any noticeable difference, given that the biggest 
model (RAM wise) is just 4GB. And it is a myth for most practical cases 
that 64bit code is automatically faster (or better) than 32bit code. 
Beside an additional problem that any unofficial 64bit ARM distros are 
facing is properly supporting the 32bit GPU, which can cause rather a 
penalty then any serious improvement in performance.
Just recompiling C code for 64bit target rather than 32bit just doesn't 
make things go faster automagically (that applies not only to ARM, but 
x86/64 processors as well). A /long/ will still be a /long/ and hence 
32bit, which might on 64bit wide CPU registers need additional 
instructions to deal with the superfluous 32bits in the register. Only 
dealing for doubles (A LOT!) might make a substantial difference, if the 
compiler library is written that way. And newer instructions to move 
memory usually are only of advantage when working in a +4GB 
environment.  What ever gain you make in a 4GB environment might simply 
be lost by dealing with additional overhead with the default data types, 
and you can bet that there only a handful if any applications in Linux 
land that have been rewritten to use different data types on different 
CPU architectures...


Ralf



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Re: [Freedos-user] FreeDOS is slow in Raspberry 4

[Ralf Quint]

On 3/19/2020 6:08 AM, Swap Jim via Freedos-user wrote:

On 2020-03-18 19:34, Jim Hall wrote:

My *dmesg* output shows it is a plain Raspberry Pi 3B:

[ 0.00] OF: fdt: Machine model: Raspberry Pi 3 Model B


Not that it matters for me. I used it as a "desktop" system for about 
a week, as an experiment, before I reinstalled it with Fedora ARM 
Server 30 and used it as a mini-server for our house. It's a print 
server, an SSH-based file server, and a web server that I use to 
develop websites.


Can you also please give me what /proc/cpuinfo tells you? I'm about to 
buy one so I need to be very certain that it's not a 3B+ model. 


What is supposed to be wrong with the 3B+ model?

Ralf



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Re: [Freedos-user] FreeDOS is slow in Raspberry 4

[Swap Jim via Freedos-user]

That's a nice suggestion. Thank you.

On 2020-03-19 16:59, David McMackins wrote:

On 3/18/20 12:21 PM, Ralf Quint wrote:

On 3/18/2020 10:02 AM, Swap Jim via Freedos-user wrote:


And in the meantime I'll try Fedora ARM, just in case it matters on
the RPi4.

FAIK, Rasbian is the best supported distro on the RPi4B+ (hardware
wise). And beside that Raspberry.org itself otherwise only promotes
Ubuntu. Fedora/Pidora was dropped at least a couple of years ago, so I
am not sure that you will be able to yield any better results using an
ARM based Fedora.

I still think that the problem is that QEMU doesn't take into account
the new capabilities of the 4B+ over the 3B+, not only CPU wise, but
also video (4K dual screen vs 1080p single), USB (3.0 vs 2.0) and
networking (true Gigabit Ethernet vs Gigiabit over USB 2.0, limited to
300MBit/sec), and defaults (at least for the video part, maybe) to a
lower performing generic "fallback" mode.

Ralf




It's worth noting that Raspbian is still only distributed in 32-bit
form, failing to take full advantage of the 64-bit ARM processor on the
Pi 4. If some other distribution is built for arm64, that may well
perform better than Raspbian even though it is the best "supported" OS.

The 32-bit distribution was a conscious decision by the Raspberry Pi
Foundation to maintain binary compatibility with older Pi boards so that
newcomers would not be confused about which download to choose.

I don't know how much of an effect running in 32-bit mode has on the
performance of the newer CPU, but I thought it was worth mentioning as a
possible reason why an unofficial distribution might run better on a Pi 4.

Regards,

David E. McMackins II
www.mcmackins.org www.delwink.com



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Re: [Freedos-user] FreeDOS is slow in Raspberry 4

[David McMackins]

On 3/18/20 12:21 PM, Ralf Quint wrote:
> On 3/18/2020 10:02 AM, Swap Jim via Freedos-user wrote:
>>
>> And in the meantime I'll try Fedora ARM, just in case it matters on
>> the RPi4. 
> FAIK, Rasbian is the best supported distro on the RPi4B+ (hardware
> wise). And beside that Raspberry.org itself otherwise only promotes
> Ubuntu. Fedora/Pidora was dropped at least a couple of years ago, so I
> am not sure that you will be able to yield any better results using an
> ARM based Fedora.
> 
> I still think that the problem is that QEMU doesn't take into account
> the new capabilities of the 4B+ over the 3B+, not only CPU wise, but
> also video (4K dual screen vs 1080p single), USB (3.0 vs 2.0) and
> networking (true Gigabit Ethernet vs Gigiabit over USB 2.0, limited to
> 300MBit/sec), and defaults (at least for the video part, maybe) to a
> lower performing generic "fallback" mode.
> 
> Ralf
> 
> 

It's worth noting that Raspbian is still only distributed in 32-bit
form, failing to take full advantage of the 64-bit ARM processor on the
Pi 4. If some other distribution is built for arm64, that may well
perform better than Raspbian even though it is the best "supported" OS.

The 32-bit distribution was a conscious decision by the Raspberry Pi
Foundation to maintain binary compatibility with older Pi boards so that
newcomers would not be confused about which download to choose.

I don't know how much of an effect running in 32-bit mode has on the
performance of the newer CPU, but I thought it was worth mentioning as a
possible reason why an unofficial distribution might run better on a Pi 4.

Regards,

David E. McMackins II
www.mcmackins.org www.delwink.com



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Re: [Freedos-user] FreeDOS is slow in Raspberry 4

[Swap Jim via Freedos-user]

On 2020-03-18 19:34, Jim Hall wrote:

My *dmesg* output shows it is a plain Raspberry Pi 3B:

[ 0.00] OF: fdt: Machine model: Raspberry Pi 3 Model B


Not that it matters for me. I used it as a "desktop" system for about a 
week, as an experiment, before I reinstalled it with Fedora ARM Server 
30 and used it as a mini-server for our house. It's a print server, an 
SSH-based file server, and a web server that I use to develop websites.


Can you also please give me what /proc/cpuinfo tells you? I'm about to 
buy one so I need to be very certain that it's not a 3B+ model.




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Re: [Freedos-user] FreeDOS is slow in Raspberry 4

[Louis Santillan]

Something to note in the original bug report is that CFLAGS chosen are
not optimal for performance (`make 'CFLAGS=-Wall -g -O2 -w'`).
Specifically, the `-g` and `-O2`  flags should probably be changed.

`-g` [0] adds debugging info which will make the QEMU binary larger,
and produce code & data to allow instrumenting and debugging at
runtime.  This will blow cache performance since more code & data
overflow the cache.  I recommend removing this all together.

`-O2` [1] instructs the compiler to enable all performance options
that do not involve a space-time tradeoff.  Generally `-O3` is
considered to produce the most "optimal" code, `-Os` is beneficial for
CPUs with small caches and `-Ofast` can enable further performance
potentially at the cost of program execution correctness.

I recommend trying `-O3` or `-Ofast` without `-g` and retesting/rebenchmarking.


[0] https://gcc.gnu.org/onlinedocs/gcc/Debugging-Options.html
[1] https://gcc.gnu.org/onlinedocs/gcc/Optimize-Options.html#Optimize-Options

On Wed, Mar 18, 2020 at 1:48 PM Jim Hall  wrote:
>
>
>
> On Wed, Mar 18, 2020 at 3:00 PM Eric Auer  wrote:
>>
>>
>> Hi Ralf,
>>
>> >> How about first installing to a directory or diskimage stored
>> >> in a ramdisk on the host OS, then copying that to mass storage?
>>
>> > This would be a bit like the old chicken and egg problem. The time you
>> > would spend to copy the contents of the FreeDOS distro from the SD card
>> > to a RAM disk on the RPi is likely not much faster...
>>
>> I expect it to be much faster because: You only read from the
>> slow SD card and you read fewer, larger files. The bad parts,
>> writing many small files, would be on the fast ramdisk side.
>> Also, you can start from a FreeDOS ISO on the SD card, which
>> again is only one big file to copy from the web to the card.
>> When done, you copy one big file, the diskimage, once from
>> the ramdisk to the SD card :-)
>> [..]
>
>
> Someone had suggested that option to me - install FreeDOS to a HD image in a 
> RAM drive, then copy the HD image back to storage.
>
> But I didn't want to explain those extra steps in my article. And really, 
> installing FreeDOS on QEMU+RPi takes longer, but it's not "all day" long. 
> It's more like "start the install, and make a cup of coffee while the install 
> finishes." For a one-time thing, it's not too bad.
>
>
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Re: [Freedos-user] FreeDOS is slow in Raspberry 4

[Jim Hall]

On Wed, Mar 18, 2020 at 3:00 PM Eric Auer  wrote:

>
> Hi Ralf,
>
> >> How about first installing to a directory or diskimage stored
> >> in a ramdisk on the host OS, then copying that to mass storage?
>
> > This would be a bit like the old chicken and egg problem. The time you
> > would spend to copy the contents of the FreeDOS distro from the SD card
> > to a RAM disk on the RPi is likely not much faster...
>
> I expect it to be much faster because: You only read from the
> slow SD card and you read fewer, larger files. The bad parts,
> writing many small files, would be on the fast ramdisk side.
> Also, you can start from a FreeDOS ISO on the SD card, which
> again is only one big file to copy from the web to the card.
> When done, you copy one big file, the diskimage, once from
> the ramdisk to the SD card :-)
> [..]


Someone had suggested that option to me - install FreeDOS to a HD image in
a RAM drive, then copy the HD image back to storage.

But I didn't want to explain those extra steps in my article. And really,
installing FreeDOS on QEMU+RPi takes longer, but it's not "all day" long.
It's more like "start the install, and make a cup of coffee while the
install finishes." For a one-time thing, it's not too bad.
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Re: [Freedos-user] FreeDOS is slow in Raspberry 4

[Ralf Quint]

On 3/18/2020 12:58 PM, Eric Auer wrote:



The only way you could possibly speed this up (at least on a RPi4B+)
would be to use a USB media (external hard drive/SSD), with the
RPi4B+ being significantly faster than previous models...

Yes. It always is something to check how fast the USB and LAN
of Raspberry style computers of various brands actually are.
Luckily benchmarks exist on the web :-) Alas, SBC rarely have
SATA connectors, so USB3 it will be. But even a SSD with USB2
is a lot faster than SD because of the much better IOPS :-)

As I mentioned, the RPi4B+ has a full USB 3.0 controller now, working 
with full 3.0 speed without interference from the Ethernet traffic 
anymore. I tested it, in fact I have a USB 3.0 external 2.5" HDD 
connected to mine, that's where all the data for my various SQL, email 
and web sites tests is... ;-)


Ralf


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Re: [Freedos-user] FreeDOS is slow in Raspberry 4

[Eric Auer]

Hi Ralf,

>> How about first installing to a directory or diskimage stored
>> in a ramdisk on the host OS, then copying that to mass storage?

> This would be a bit like the old chicken and egg problem. The time you
> would spend to copy the contents of the FreeDOS distro from the SD card
> to a RAM disk on the RPi is likely not much faster...

I expect it to be much faster because: You only read from the
slow SD card and you read fewer, larger files. The bad parts,
writing many small files, would be on the fast ramdisk side.
Also, you can start from a FreeDOS ISO on the SD card, which
again is only one big file to copy from the web to the card.
When done, you copy one big file, the diskimage, once from
the ramdisk to the SD card :-)

> The only way you could possibly speed this up (at least on a RPi4B+)
> would be to use a USB media (external hard drive/SSD), with the
> RPi4B+ being significantly faster than previous models...

Yes. It always is something to check how fast the USB and LAN
of Raspberry style computers of various brands actually are.
Luckily benchmarks exist on the web :-) Alas, SBC rarely have
SATA connectors, so USB3 it will be. But even a SSD with USB2
is a lot faster than SD because of the much better IOPS :-)

Eric



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Re: [Freedos-user] FreeDOS is slow in Raspberry 4

[Ralf Quint]

On 3/18/2020 11:56 AM, Eric Auer wrote:

Installing FreeDOS*on the Raspberry Pi *will take a long time regardless of
what options you use in QEMU. It's because of the high disk I/O when you
install an operating system like FreeDOS. It's made worse by doing it
inside an emulator, but the biggest slowdown when *installing* is the
storage device on the Raspberry Pi.

How about first installing to a directory or diskimage stored
in a ramdisk on the host OS, then copying that to mass storage?


This would be a bit like the old chicken and egg problem. The time you 
would spend to copy the contents of the FreeDOS distro from the SD card 
to a RAM disk on the RPi is likely not much faster than trying to 
install from an SD card.


The only way you could possibly speed this up (at least on a RPi4B+) 
would be to use a USB media (external hard drive/SSD), with the RPi4B+ 
being significantly faster than previous models due to having a 
dedicated USB 3.0 controller now, which also isn't encumbered anymore by 
having to play network controller for the Ethernet port...


Ralf




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Re: [Freedos-user] FreeDOS is slow in Raspberry 4

[Eric Auer]

Hi Jim!

> Installing FreeDOS on the Raspberry Pi will take a long time regardless of
> what options you use in QEMU. It's because of the high disk I/O when you
> install an operating system like FreeDOS. It's made worse by doing it
> inside an emulator, but the biggest slowdown when *installing* is the
> storage device on the Raspberry Pi.

How about first installing to a directory or diskimage stored
in a ramdisk on the host OS, then copying that to mass storage?

MicroSD cards and many USB sticks are notoriously bad in their
I/O per second rating even when they advertise dozens or many
MB/s transfer speed for large files. For Raspberry style use,
the "Application performance class" is important: A1 promises
500 writes (1500 reads) per second, A2 2000 writes (4000 reads)
and yes A2 ratings are rare in spite of all those cards which
proudly announce dozens of MB/s for video recording.

Some tiny computers use eMMC disks, those are significantly
faster in everyday use. I even enjoyed compiling kernels on
one of those. They usually are pre-soldered to the SBC board.

Similar issues affect USB flash sticks: Even "fast" ones
drop to the low single digit MB/s when you attempt to use
them with many small writes and an unlucky filesystem choice
(I would like to know which filesystems are most bearable
in that context, in Linux?) with the only exception being
SSD style USB sticks which actually advertise having high
write IOPS. A bit of a luxury but probably works fine :-)

Regards, Eric

PS: Interesting thought that Raspian uses the right endian
for x86 simulations. Would be nice to see some benchmarks,
maybe also comparing different virtual PCs beyond Qemu :-)

> My RPi3B has a SanDisk Ultra 64GB microSDXC UHS-I U1A1 card.




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Re: [Freedos-user] FreeDOS is slow in Raspberry 4

[Mateusz Viste]

On 18/03/2020 17:16, Ralf Quint wrote:
What some people are forgetting (had the exact kind of discussion in a 
vintage computer forum just a few days ago) is that in this case, QEMU 
needs to completely emulate an x86 CISC CPU on an ARM RISC CPU, 
including converting all data on the fly between little-endian and 
big-endian format on the fly, all the time.


All true, with one exception: raspbian runs the ARM SoC in little-endian 
mode, so no conversion needed there.


Mateusz


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Re: [Freedos-user] FreeDOS is slow in Raspberry 4

[Jim Hall]

On Wed, Mar 18, 2020 at 12:36 PM Jon Brase  wrote:

>
> On 3/18/20 11:44 AM, Jim Hall wrote:
>
> Actually, I think it's a problem on the Raspberry Pi 4. I've heard from a
> few folks since the RPi4 came out that my how-to about running FreeDOS on
> the Raspberry Pi (via QEMU)
>  results
> in a very slow FreeDOS. But I've only heard from people about the Raspberry
> Pi 4. The RPi3 seems to work okay. I have a Raspberry Pi 3, and it works
> fine. I've run my RPi3 with both Raspbian and Fedora ARM with the same
> results, so I don't think it's a distro issue, either.
>
> The Raspberry Pi (as lease version 3) is fast enough to emulate a '486 or
> Pentium CPU well enough to run DOOM and AsEasyAs and other DOS games and
> applications without lag.
>
>
> On a Pi 2, I'm getting the same slow video updates he describes, at least
> in text mode (haven't tried a graphical mode yet), but the emulated CPU
> seems to be running fast enough. Then again, the install process is taking
> a fair while, but I'm not sure it's slower than an install of similar size
> would be on legacy hardware.
>


Installing FreeDOS on the Raspberry Pi will take a long time regardless of
what options you use in QEMU. It's because of the high disk I/O when you
install an operating system like FreeDOS. It's made worse by doing it
inside an emulator, but the biggest slowdown when *installing* is the
storage device on the Raspberry Pi.

My RPi3B has a SanDisk Ultra 64GB microSDXC UHS-I U1A1 card. The U1 is
designed to support 1080p video recording (such as you might use in a GoPro
camera) at minimum serial write speeds of 10MB/s. By comparison, a V60 is
aimed at cameras that do 4K video and has a minimum sequential write speed
of 60MB/s. Using a V60 microSD card or even a V30 (30MB/s) would probably
give noticeably better disk I/O performance (up to 3x faster).


Jim
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Re: [Freedos-user] FreeDOS is slow in Raspberry 4

[Ralf Quint]

On 3/18/2020 10:34 AM, Jim Hall wrote:

My *dmesg* output shows it is a plain Raspberry Pi 3B:
[ 0.00] OF: fdt: Machine model: Raspberry Pi 3 Model B


My RPi4B+ shows


[    0.00] Booting Linux on physical CPU 0x0
[    0.00] Linux version 4.19.97-v7l+ (dom@buildbot) (gcc version 
4.9.3 (crosstool-NG crosstool-ng-1.22.0-88-g8460611)) #1294 SMP Thu 
Jan 30 13:21:14 GMT 2020
[    0.00] CPU: ARMv7 Processor [410fd083] revision 3 (ARMv7), 
cr=30c5383d

[    0.00] CPU: div instructions available: patching division code
[    0.00] CPU: PIPT / VIPT nonaliasing data cache, PIPT 
instruction cache

[    0.00] OF: fdt: Machine model: Raspberry Pi 4 Model B Rev 1.1




Not that it matters for me. I used it as a "desktop" system for about 
a week, as an experiment, before I reinstalled it with Fedora ARM 
Server 30 and used it as a mini-server for our house. It's a print 
server, an SSH-based file server, and a web server that I use to 
develop websites.


That's what my RPi4B+ now does too, though I am running Apache and MySQL 
for testing web sites and I am about to use it as a test bed for some 
email server trials in the next few days. Running this on the default 
Raspbian though, as I am also playing with cross-platform development 
using FreePascal/Lazarus on it...


Ralf




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Re: [Freedos-user] FreeDOS is slow in Raspberry 4

[Jim Hall]

My *dmesg* output shows it is a plain Raspberry Pi 3B:

[0.00] OF: fdt: Machine model: Raspberry Pi 3 Model B


Not that it matters for me. I used it as a "desktop" system for about a
week, as an experiment, before I reinstalled it with Fedora ARM Server 30
and used it as a mini-server for our house. It's a print server, an
SSH-based file server, and a web server that I use to develop websites.




On Wed, Mar 18, 2020 at 12:06 PM Ralf Quint  wrote:

> On 3/18/2020 9:44 AM, Jim Hall wrote:
>
> Actually, I think it's a problem on the Raspberry Pi 4. I've heard from a
> few folks since the RPi4 came out that my how-to about running FreeDOS on
> the Raspberry Pi (via QEMU)
>  results
> in a very slow FreeDOS. But I've only heard from people about the Raspberry
> Pi 4. The RPi3 seems to work okay. I have a Raspberry Pi 3, and it works
> fine. I've run my RPi3 with both Raspbian and Fedora ARM with the same
> results, so I don't think it's a distro issue, either.
>
> The Raspberry Pi (as lease version 3) is fast enough to emulate a '486 or
> Pentium CPU well enough to run DOOM and AsEasyAs and other DOS games and
> applications without lag.
>
> Well, what kind of Raspberry Pi3 do you have? A "plain" 3B or a 3B+?
>
> The 3B+ has a 1.4GHz Cortex-A53 CPU, while the 4B+ has a 1.5GHz Cortex-A72
> CPU. And given that a 4B+ is on average 4x as fast as a 3B+, with only
> 0.1GHz difference in clock speed, there could be that QEMU just isn't using
> the 4B+ CPU properly.
>
> I haven't run QEMU on my RPi4B+ (beside that it is sitting off-site at a
> client right now) but everything I tested with it, in the way I intended to
> use it, it was a significantly, noticeable difference. So from the plain
> capabilities of the 4B+, there should be no reason why it would be so slow
> in QEMU.
>
> Well, the GPU part of the SoC chip could of course be culprit here, now
> that the 4B+ by default supports a two monitors. Can someone run a
> "speedtest" between a 3B+ and a 4B+ with an application that doesn't use
> any screen output to possibly verify this?
>
> Ralf
>
> PS: FWIW, I have not been able to run WCG via BOINC on the RPi4B+, getting
> the message that the project doesn't have any work units for computers of
> the type "arm-unknown-linux-gnueabihf", while it was running just fine on
> my RPi3B+.
>
>
>
>
> 
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Re: [Freedos-user] FreeDOS is slow in Raspberry 4

[Ralf Quint]

On 3/18/2020 10:02 AM, Swap Jim via Freedos-user wrote:


And in the meantime I'll try Fedora ARM, just in case it matters on 
the RPi4. 
FAIK, Rasbian is the best supported distro on the RPi4B+ (hardware 
wise). And beside that Raspberry.org itself otherwise only promotes 
Ubuntu. Fedora/Pidora was dropped at least a couple of years ago, so I 
am not sure that you will be able to yield any better results using an 
ARM based Fedora.


I still think that the problem is that QEMU doesn't take into account 
the new capabilities of the 4B+ over the 3B+, not only CPU wise, but 
also video (4K dual screen vs 1080p single), USB (3.0 vs 2.0) and 
networking (true Gigabit Ethernet vs Gigiabit over USB 2.0, limited to 
300MBit/sec), and defaults (at least for the video part, maybe) to a 
lower performing generic "fallback" mode.


Ralf


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Re: [Freedos-user] FreeDOS is slow in Raspberry 4

[Ralf Quint]

On 3/18/2020 9:44 AM, Jim Hall wrote:
Actually, I think it's a problem on the Raspberry Pi 4. I've heard 
from a few folks since the RPi4 came out that my how-to about running 
FreeDOS on the Raspberry Pi (via QEMU) 
 results 
in a very slow FreeDOS. But I've only heard from people about the 
Raspberry Pi 4. The RPi3 seems to work okay. I have a Raspberry Pi 3, 
and it works fine. I've run my RPi3 with both Raspbian and Fedora ARM 
with the same results, so I don't think it's a distro issue, either.


The Raspberry Pi (as lease version 3) is fast enough to emulate a '486 
or Pentium CPU well enough to run DOOM and AsEasyAs and other DOS 
games and applications without lag.


Well, what kind of Raspberry Pi3 do you have? A "plain" 3B or a 3B+?

The 3B+ has a 1.4GHz Cortex-A53 CPU, while the 4B+ has a 1.5GHz 
Cortex-A72 CPU. And given that a 4B+ is on average 4x as fast as a 3B+, 
with only 0.1GHz difference in clock speed, there could be that QEMU 
just isn't using the 4B+ CPU properly.


I haven't run QEMU on my RPi4B+ (beside that it is sitting off-site at a 
client right now) but everything I tested with it, in the way I intended 
to use it, it was a significantly, noticeable difference. So from the 
plain capabilities of the 4B+, there should be no reason why it would be 
so slow in QEMU.


Well, the GPU part of the SoC chip could of course be culprit here, now 
that the 4B+ by default supports a two monitors. Can someone run a 
"speedtest" between a 3B+ and a 4B+ with an application that doesn't use 
any screen output to possibly verify this?


Ralf

PS: FWIW, I have not been able to run WCG via BOINC on the RPi4B+, 
getting the message that the project doesn't have any work units for 
computers of the type "arm-unknown-linux-gnueabihf", while it was 
running just fine on my RPi3B+.





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Re: [Freedos-user] FreeDOS is slow in Raspberry 4

[Swap Jim via Freedos-user]

So it's feasible! That's great news! A 486 or Pentium would be great!

Can you give me the links for these discussions? I'll visiting them in 
hope that maybe someone in the future might have found a solution.


And in the meantime I'll try Fedora ARM, just in case it matters on the 
RPi4.


Just some fun background: This is a project to create a dedicated DOS 
computer (it'll boot Linux and then straight to QEMU and FreeDOS) to use 
as a place to calm down and be more productive. And play classic games ;-)


On 2020-03-18 18:44, Jim Hall wrote:
Actually, I think it's a problem on the Raspberry Pi 4. I've heard from 
a few folks since the RPi4 came out that my how-to about running FreeDOS 
on the Raspberry Pi (via QEMU) 
 results 
in a very slow FreeDOS. But I've only heard from people about the 
Raspberry Pi 4. The RPi3 seems to work okay. I have a Raspberry Pi 3, 
and it works fine. I've run my RPi3 with both Raspbian and Fedora ARM 
with the same results, so I don't think it's a distro issue, either.


The Raspberry Pi (as lease version 3) is fast enough to emulate a '486 
or Pentium CPU well enough to run DOOM and AsEasyAs and other DOS games 
and applications without lag.


On Wed, Mar 18, 2020 at 11:17 AM Ralf Quint > wrote:


On 3/18/2020 6:31 AM, Swap Jim via Freedos-user wrote:
 > FreeDOS is very, very slow on QEMU running in a Raspberry 4.
 >
 > It's drawing the screen line by line when I do a DIR on C:\, with
only
 > 7 directories and files in it. It's worse in full screen.
 >
 > For those of you that run FreeDOS on a Raspberry, can you offer a
tip
 > to make it go faster?
 >
 > Here is some more info.
 >
 > It's a Raspberry Pi 4 B+ with 4GB of RAM. I'm running the latest
 > Raspbian. I couldn't manage to install QEMU from apt, so I've
compiled
 > version 4.2.0 with these flags:
 >
 >   ./configure --target-list=i386-softmmu --disable-vnc --enable-sdl
 >   make 'CFLAGS=-Wall -g -O2 -w'

That is a problem of QEMU, not FreeDOS.

What some people are forgetting (had the exact kind of discussion in a
vintage computer forum just a few days ago) is that in this case, QEMU
needs to completely emulate an x86 CISC CPU on an ARM RISC CPU,
including converting all data on the fly between little-endian and
big-endian format on the fly, all the time.

This is a complete different situation for example than emulating a
16bit x86 PC system on a 64bit x86 host system, like running DOSBox or
VirtualBox. While the later doesn't (in 64bit mode) support 16bit
operation anymore, it is still the same basic underlying CPU
architecture, and the same data "endian-ness".

Ralf


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Re: [Freedos-user] FreeDOS is slow in Raspberry 4

[Jim Hall]

Actually, I think it's a problem on the Raspberry Pi 4. I've heard from a
few folks since the RPi4 came out that my how-to about running FreeDOS on
the Raspberry Pi (via QEMU)
 results
in a very slow FreeDOS. But I've only heard from people about the Raspberry
Pi 4. The RPi3 seems to work okay. I have a Raspberry Pi 3, and it works
fine. I've run my RPi3 with both Raspbian and Fedora ARM with the same
results, so I don't think it's a distro issue, either.

The Raspberry Pi (as lease version 3) is fast enough to emulate a '486 or
Pentium CPU well enough to run DOOM and AsEasyAs and other DOS games and
applications without lag.

On Wed, Mar 18, 2020 at 11:17 AM Ralf Quint  wrote:

> On 3/18/2020 6:31 AM, Swap Jim via Freedos-user wrote:
> > FreeDOS is very, very slow on QEMU running in a Raspberry 4.
> >
> > It's drawing the screen line by line when I do a DIR on C:\, with only
> > 7 directories and files in it. It's worse in full screen.
> >
> > For those of you that run FreeDOS on a Raspberry, can you offer a tip
> > to make it go faster?
> >
> > Here is some more info.
> >
> > It's a Raspberry Pi 4 B+ with 4GB of RAM. I'm running the latest
> > Raspbian. I couldn't manage to install QEMU from apt, so I've compiled
> > version 4.2.0 with these flags:
> >
> >   ./configure --target-list=i386-softmmu --disable-vnc --enable-sdl
> >   make 'CFLAGS=-Wall -g -O2 -w'
>
> That is a problem of QEMU, not FreeDOS.
>
> What some people are forgetting (had the exact kind of discussion in a
> vintage computer forum just a few days ago) is that in this case, QEMU
> needs to completely emulate an x86 CISC CPU on an ARM RISC CPU,
> including converting all data on the fly between little-endian and
> big-endian format on the fly, all the time.
>
> This is a complete different situation for example than emulating a
> 16bit x86 PC system on a 64bit x86 host system, like running DOSBox or
> VirtualBox. While the later doesn't (in 64bit mode) support 16bit
> operation anymore, it is still the same basic underlying CPU
> architecture, and the same data "endian-ness".
>
> Ralf
>
>
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Re: [Freedos-user] FreeDOS is slow in Raspberry 4

[Ralf Quint]

On 3/18/2020 6:31 AM, Swap Jim via Freedos-user wrote:

FreeDOS is very, very slow on QEMU running in a Raspberry 4.

It's drawing the screen line by line when I do a DIR on C:\, with only 
7 directories and files in it. It's worse in full screen.


For those of you that run FreeDOS on a Raspberry, can you offer a tip 
to make it go faster?


Here is some more info.

It's a Raspberry Pi 4 B+ with 4GB of RAM. I'm running the latest 
Raspbian. I couldn't manage to install QEMU from apt, so I've compiled 
version 4.2.0 with these flags:


  ./configure --target-list=i386-softmmu --disable-vnc --enable-sdl
  make 'CFLAGS=-Wall -g -O2 -w' 


That is a problem of QEMU, not FreeDOS.

What some people are forgetting (had the exact kind of discussion in a 
vintage computer forum just a few days ago) is that in this case, QEMU 
needs to completely emulate an x86 CISC CPU on an ARM RISC CPU, 
including converting all data on the fly between little-endian and 
big-endian format on the fly, all the time.


This is a complete different situation for example than emulating a 
16bit x86 PC system on a 64bit x86 host system, like running DOSBox or 
VirtualBox. While the later doesn't (in 64bit mode) support 16bit 
operation anymore, it is still the same basic underlying CPU 
architecture, and the same data "endian-ness".


Ralf


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[Freedos-user] FreeDOS is slow in Raspberry 4

[Swap Jim via Freedos-user]

FreeDOS is very, very slow on QEMU running in a Raspberry 4.

It's drawing the screen line by line when I do a DIR on C:\, with only 7 
directories and files in it. It's worse in full screen.


For those of you that run FreeDOS on a Raspberry, can you offer a tip to 
make it go faster?


Here is some more info.

It's a Raspberry Pi 4 B+ with 4GB of RAM. I'm running the latest 
Raspbian. I couldn't manage to install QEMU from apt, so I've compiled 
version 4.2.0 with these flags:


  ./configure --target-list=i386-softmmu --disable-vnc --enable-sdl
  make 'CFLAGS=-Wall -g -O2 -w'



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