[Bug gcov-profile/99105] profile streaming scales poorly to projects with many source files

[hubicka at ucw dot cz]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=99105

--- Comment #7 from Jan Hubicka <hubicka at ucw dot cz> ---
> > Because user apps may do funny thins with stdio such as they do with
> > malloc.  Fewer library stuff we rely on, the less likely we will hit the
> > problems.  So I am not sure if simply fixing i/o isn't better approach,
> > but I do not know.
> 
> Sure. With the patch, we don't rely on any glibc feature. We will just
> use a default read/write IO (which uses a buffering internally).

Well, buffered i/o is library feature :)
> > 2727 gcda files, 44MB overall, 4MB xz compressed tar file.
> > I am actually surprised that the file count is quite small. Firefox has
> > more...
> 
> To be honest, it's very small file size. I would expect these files should
> definitely live in a page cache.

For Firefox it is 2500 gcda files, 75MB overall, 6MB compressed.
> 
> What type of disk do you use?

/dev/nvme0n1     7QG00HVT             Seagate FireCuda 520 SSD ZP1000GM30002  
1           1.00  TB /   1.00  TB    512   B +  0 B STNSC014

(it is our new zen3 machine)

Honza