[R-pkg-devel] Slow down in R 4.2.x

[Tomas Kalibera]

On 7/1/22 11:10, Johannes Ranke wrote:
> Dear list,
>
> independent of the thread on this list about slow examples on R 4.2 on windows
> I have discovered over the last few days that some of my benchmarks (look for
> t4 and t9) run by a factor of 3 slower on R 4.2.x than on R 4.1.3 [1].
>
> This is on Linux, using my own backported R packages for R 4.2.x and locally
> compiled versions (with default configure options) of R-4-1-branch on two
> different CPUs. The results for R 4.2.1 are only slightly modulated by the use
> of different BLAS version (openblas-serial versus atlas versus lapack).
>
> I also tested the R 4.0.4 version that is part of Debian bullseye, it is as
> fast as the locally compiled R 4.1.3.
>
> I went through the NEWS for R 4.2.0 (because the first slow results were
> obtained using that version), but the only change I could imagine causing such
> a change is the additional check of the length of the arguments && and ||.
>
> Any other thoughts?

I can reproduce slowdown in one of your tests:

library(mkin)
FOCUS_D <- subset(FOCUS_2006_D, value != 0)
SFO_SFO <- mkinmod(
   parent = mkinsub("SFO", "m1"),
   m1 = mkinsub("SFO"))
FOMC_SFO <- mkinmod(
   parent = mkinsub("FOMC", "m1"),
   m1 = mkinsub("SFO"))
DFOP_SFO <- mkinmod(
   parent = mkinsub("FOMC", "m1"),
   m1 = mkinsub("SFO"))

mmkin_bench <- function(models, datasets, error_model = "const") {
   mmkin(models, datasets, error_model = error_model, cores = 1, quiet = 
TRUE)
}

t4 <- system.time(mmkin_bench(list(SFO_SFO, FOMC_SFO, DFOP_SFO), 
list(FOCUS_D), error_model = "tc"))[["elapsed"]]

This is slower in R 4-devel than R 4.1 because of bug fixes in DLL info 
interface (PR#16446, r80285). "perf" tool on Linux shows extra time 
spent in R_registerSymbolEptr and R_WeakRefKey. This is because of 
repeated calls to getLoadedDLLs(), via repeated calls to 
inline::getDynLib(x$cf)[["name"]]

Perhaps one could save dll_info, once computed in mkin, alongside "cf" 
in the model, instead of re-computing it every time?

Best
Tomas


>
> Johannes
>
> [1] https://pkgdown.jrwb.de/mkin/articles/web_only/benchmarks.html#results
>
>
>
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>
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