On Tue, 9 Sep 2025, Julian Ganz wrote:
September 7, 2025 at 10:21 PM, "BALATON Zoltan" wrote:
I have uploaded some PPC binaries for the STREAM benchmark that I tested with
before here:
http://zero.eik.bme.hu/~balaton/qemu/stream-test.zip
which may excercise this if run on sam460ex or ppce500 machines but I don't
have a scripted test case for that. There is some docs on how to run Linux on
these machines here:
https://www.qemu.org/docs/master/system/target-ppc.html
After spending too much time looking for usable root-images (and then
giving up and just stuffing the executables in an ext2), I got to run
these beanchmarks on Linux 4.4.5 configured for the Sam460ex from [1].
Thank you for testing this.
I ran streamPPCpowerpcO3 on qemu with these patches:
-------------------------------------------------------------
Function Best Rate MB/s Avg time Min time Max time
Copy: 2867.6 0.056828 0.055795 0.061792
Scale: 1057.5 0.153282 0.151305 0.158115
Add: 1308.8 0.187095 0.183380 0.193672
Triad: 1111.6 0.220863 0.215902 0.230440
-------------------------------------------------------------
After doing a clean build, with the fans still audible:
-------------------------------------------------------------
Function Best Rate MB/s Avg time Min time Max time
Copy: 2932.9 0.055131 0.054554 0.055667
Scale: 1067.9 0.151520 0.149832 0.155000
Add: 1324.9 0.184807 0.181150 0.191386
Triad: 1122.0 0.220080 0.213896 0.229302
-------------------------------------------------------------
What was different between the above two runs? I guess maybe one is with
plugins disabled but it's not clear from the description.
On qemu (6a9fa5ef3230a7d51e0d953a59ee9ef10af705b8) without these
patches, but plugins enabled:
-------------------------------------------------------------
Function Best Rate MB/s Avg time Min time Max time
Copy: 2972.1 0.054407 0.053834 0.054675
Scale: 1068.6 0.151503 0.149726 0.154594
Add: 1327.6 0.185160 0.180784 0.193181
Triad: 1127.2 0.219249 0.212915 0.229230
-------------------------------------------------------------
And on qemu (6a9fa5ef3230a7d51e0d953a59ee9ef10af705b8) without these
patches, with plugins disabled:
-------------------------------------------------------------
Function Best Rate MB/s Avg time Min time Max time
Copy: 2983.4 0.055141 0.053630 0.060013
Scale: 1058.3 0.152353 0.151186 0.155072
Add: 1323.9 0.184707 0.181279 0.188868
Triad: 1128.2 0.218674 0.212734 0.230314
-------------------------------------------------------------
I fail to see any significant indication that these patches, or
plugins in general, would result in a degredation of performance.
With worst case Copy test it seems to be about 3.5% (and about 1.7% with
plugins disabled?) and should be less than that normally so it does not
add much more overhead to plugins than there is already so this should be
acceptable. It may still be interesting to see if the overhead with
plugins disabled can be avoided with a similar way as logging does it.
Regards,
BALATON Zoltan
Regards,
Julian
[1]: http://www.supertuxkart-amiga.de/amiga/sam.html#downloads
