Hi, thanks for the answers.
On 2023-11-28 01:51:46 +0100, Maxime Devos wrote: > (set! copy-file improved-copy-file) > > This replacement 100% functioning assumes no inlining, nobody capturing the > old copy-file on the top-level, nobody calling the C function directly ... In that case this is what I will use. There should be no fundamental problem if some case will be missed, since I am doing performance optimization only, correctness is not affected. > > If the original copy-file is implemented in Scheme, then to avoid inlining > problems, the module defining copy-file should do > > (set! copy-file copy-file). It looks like it is defined inside libguile/filesys.c, so that is not an option. And I would like to avoid patching the Guile itself anyway. > > That way, Guile's compiler/optimizer knows that the binding is mutable and > should not inlined (well, Guile being Guile, every binding is mutable, but > now it is mutable from the perspective of the inliner too). Interesting, is there a way to do the same hint from the C code? Would there be a reason? I assume C code cannot be inlined anyway, so there is no need? > > Depending on whether 'copy-file' is just a stand-in for something else and > depending on how the better copy-file works/how it is ‘better’, it might be > better to eventually write a patch to replace copy-file with the improved > better-file, as then the improved copy-file is more widely available. (As a > long-term thing; for short-term ‘trying things out’, doing set! is much more > practical.) What I want to do is to replace (copy-file oldfile newfile) by modified version with signature (copy-file oldfile newfile [reflink]) with reflink defaulting to 'auto (see man cp for details). I expect this to be a somewhat controversial change, so I did not intend to send a patch, however I can, if you think it has a chance of getting merged. Tomas -- There are only two hard things in Computer Science: cache invalidation, naming things and off-by-one errors.
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