Performance loss with word count benchmark

[Julia Lawall]

On Fri, 29 Sep 2023, Matthew Wilcox wrote:

> On Thu, Sep 28, 2023 at 06:32:01PM +0200, Julia Lawall wrote:
> > https://github.com/kozyraki/phoenix
> >
> > The test is in phoenix-2.0
> >
> > It can be run as
> >
> > tests/word_count/word_count word_count/word_count_datafiles/word_100MB.txt
> >
> > I think you have to download the word_100MB.txt file separately.
>
> Thanks, Julia.  Bringing in some other people that care about maple tree
> performance.
>
> A quick glance at strace doesn't show much in the way of calls to mmap.
> Using strace -f to make sure I capture all the threads shows a lot of
> anon mmap calls, but mostly of 41 and 81 pages in length (164kB, 324kB).
> That might be a libc malloc artefact?
>
> Ooh, just found one that's 161 pages.  But there are a lot of calls to
> mprotect; that's going to create new VMAs, right?

Zillions of calls to mprotect.  They also come all at the same time, over
and over.  I can make some graphs to show what is going on.

julia