Re: [debian-hppa] poor performance of Debian 11 HPPA with qemu-system-hppa
Hi Nelson,
Helge Deller is the expert on this and you likely will have to wait until he returns from vacation
for an answer. I think the pasta buildd running hppa emulation is configured for one cpu although
I could be wrong. Performance is a little slower than a real 800 MHz PA8800 machine.
Some profiling likely would be helpful.
Dave
On 2021-08-14 10:35 a.m., Nelson H. F. Beebe wrote:
> In a previous message to the debian-hppa list today, I described how I
> finally got a virtual machine successfully created for running Debian
> 11 on HPPA (aka PA-RISC).
>
> On the same host
>
> Dell Precision 7920 (1 16-core CPU, 32 hyperthreads,
> 2200MHz Intel Xeon Platinum 8253,
> 384GB DDR-4 RAM);
> Ubuntu 20.04.02 LTS (Focal Fossa)
>
> I have VMs running with QEMU emulation for Alpha, ARM64, M68K, MIPS32,
> MIPS64, RISC-V64, S390x, and SPARC64, and most of them have quite
> reasonable interactive performance, making it possible to use the
> emacs editor in terminal windows and X11 windows without any serious
> response problems.
>
> However, for the new Debian 11 HPPA VM, interactive performance is a
> huge issue: shell typein sometimes gets immediate character echo, but
> frequently gets delays of 10 to 30 seconds for each input character.
> That makes it extremely hard for a fast typist to type commands and
> text: one is never sure whether input keys have been dropped.
>
> I develop mathematical software, and a large package that I'm writing
> for multiple precision arithmetic provides a testbed for evaluating VM
> performance. Most of the QEMU CPU types support multiple processors,
> but M68K and SPARC64 sun4u only permit one CPU. For HPPA, I have 4 CPUs
> and 3GB DRAM; the latter is a hard limit imposed in QEMU source code.
>
> Here is a table of running the equivalent of
>
> date; make all check ; date
>
> on these systems, using QEMU-6.0.0, unless noted. Both compilations
> and test programs are run in parallel, by internal "make -j" commands.
>
> make timing (wall clock)
>
> Debian 11 Alpha 07:43:16 -- 08:23:05 39m 49s
> Debian 11 ARM64 07:58:02 -- 08:24:45 26m 43s
> Debian 11 M68K 07:43:15 -- 08:30:56 47m 41s
> Debian 11 HPPA 13:23:16 -- 21:40:19 497m 03s
> Debian 11 HPPA 07:29:18 -- 18:07:19 638m 01s [qemu-6.1.0-rc3]
> NetBSD 9.2 HPPA 11:22:10 -- 01:25:46 843m 36s
> Debian 11 MIPS32 09:21:49 -- 10:42:41 80m 52s
> Debian 11 SPARC64 14:45:16 -- 06:19:00 933m 44s
> Debian 11 SPARC64 17:57:58 -- 04:02:42 603m 44s [qemu-6.1.0-rc3]
> Ubuntu 18.04 S390x 18:34:34 -- 19:04:36 30m 02s
> Ubuntu 20.04 S390x 18:34:35 -- 19:16:54 42m 19s
> FreeBSD 13 RISC-V64 07:41:14 -- 08:34:00 52m 46s
> FreeBSD 14 RISC-V64 08:35:27 -- 09:25:35 50m 08s
> Fedora 34 RISC-V64 07:43:17 -- 08:02:55 19m 38s
>
> >From comparison, here are results on native hardware with local disk
> (not NFS, unless indicated) [clock speed in GHz is abbreviated to G]:
>
> ArchLinux ARM32 09:57:34 -- 10:07:43 10m 09s
> Debian 11 UltraSparc T2 08:30:54 -- 08:41:18 10m 24s
> Solaris 10 UltraSparc T2 09:46:31 -- 09:59:32 13m 01s
> Ubuntu 20.04 Xeon 8253 09:34:52 -- 09:35:36 0m 44s
> CentOS 7.9 Xeon E6-1600v3 09:39:00 -- 09:39:42 0m 42s
> CentOS 7.9 Xeon E6-1600v3 10:42:43 -- 10:43:30 0m 47s [NFS]
> CentOS 7.9 EPYC 7502 2.0G 64C/128T 10:02:01 -- 10:02:27 0m 26s
> CentOS 7.9 EPYC 7502 2.5G 32C/64T 10:02:00 -- 10:02:25 0m 25s
>
> The tests produce about 62,000 total lines of text output, spread over
> about 180 files. They read no input data, and are primarily compute
> bound in loops with integer, not floating-point, arithmetic, using
> 32-bit and 64-bit integer types.
>
> I have generated machine language for representative code from the
> hotspot loop using the -S option of gcc and clang, and found that
> 64-bit arithmetic is expanded inline with 32-bit instructions on
> ARM32, HPPA, and M68K, none of which have 64-bit arithmetic
> instructions. The loop instruction counts are comparable across all
> of those systems, typically 10 to 20 instructions, compared to 5 or so
> on those CPUs that have 64-bit arithmetic.
>
> The dramatic slowdowns on HPPA and SPARC64 are a big surprise, but the
> HPPA slowdown matches the poor interactive response. The SPARC64 VM
> is much more responsive interactively, and it DOES have 64-bit integer
> arithmetic.
>
> I have not yet done profiling builds of qemu-system-hppa and
> qemu-system-sparc64, but that remains an option for further
> investigation to find out what is responsible for the slowness.
>
> I can also do profiling builds of parts of my test suite to see
> whether there are unexpected hotspots on HPPA and SPARC64 that are
> absent on other CPU types.
>
> I have physical SPARC64 hardware running Debian 11 and Solaris 10 on
> identical boxes, and have done builds of TeX Live on them with no
> difficulty. However, the slow speed of QEMU HPPA makes it impractical
> to try TeX Live builds for Debian 11 HPPA, which is disappointing.
>
> Does any list member have any idea of why QEMU emulation of HPPA and
> SPARC64 is so bad? Are there Debian kernel parameters that might be
> tweaked? Have any of you used Debian on QEMU HPPA and seen similar
> slowness compared to other CPU types?
>
> Notice from my first table above that NetBSD 9.2 on HPPA is also very
> slow, which tends to point the finger at QEMU as the source of the
> dismal performance, rather than the VM guest O/S.
>
> For the record, here is how QEMU releases downloaded from
>
> https://www.qemu.org/
> https://download.qemu.org/
>
> are built here, taking the most recent QEMU release for the sample:
>
> tar xf $prefix/src/qemu/qemu-6.1.0-rc3.tar.xz
> cd qemu-6.1.0-rc3
> unsetenv CONFIG_SITE
> mkdir build
> cd build
> env CC=cc CFLAGS=-O2 ../configure --prefix=$prefix && make all -j && make check
>
> QEMU builds require prior installation of the ninja-build package
> available on major GNU/Linux distributions. On completion, the needed
> qemu-system-xxx executables are present in the build subdirectory.
>
> On Ubuntu 20.04, the QEMU builds are clean, and pass the entire
> validation suite without any failures.
>
> -------------------------------------------------------------------------------
> - Nelson H. F. Beebe Tel: +1 801 581 5254 -
> - University of Utah FAX: +1 801 581 4148 -
> - Department of Mathematics, 110 LCB Internet e-mail: beebe@math.utah.edu -
> - 155 S 1400 E RM 233 beebe@acm.org beebe@computer.org -
> - Salt Lake City, UT 84112-0090, USA URL: http://www.math.utah.edu/~beebe/ -
> -------------------------------------------------------------------------------
>
--
John David Anglin dave.anglin@bell.net
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