Re: [PATCH 2/3] vmscan: make mapped executable pages the first class citizen

[KOSAKI Motohiro]

> > begin:       2479             2344             9659              210                0           579643
> > end:          284           232010           234142              260           772776         20917184
> > restore:      379           232159           234371              301           774888         20967849
> > 
> > The numbers show that
> > 
> > - The startup pgmajfault of 2.6.30-rc4-mm is merely 1/3 that of 2.6.29.
> >   I'd attribute that improvement to the mmap readahead improvements :-)
> > 
> > - The pgmajfault increment during the file copy is 633-630=3 vs 260-210=50.
> >   That's a huge improvement - which means with the VM_EXEC protection logic,
> >   active mmap pages is pretty safe even under partially cache hot streaming IO.
> > 
> > - when active:inactive file lru size reaches 1:1, their scan rates is 1:20.8
> >   under 10% cache hot IO. (computed with formula Dpgdeactivate:Dpgfree)
> >   That roughly means the active mmap pages get 20.8 more chances to get
> >   re-referenced to stay in memory.
> > 
> > - The absolute nr_mapped drops considerably to 1/9 during the big IO, and the
> >   dropped pages are mostly inactive ones. The patch has almost no impact in
> >   this aspect, that means it won't unnecessarily increase memory pressure.
> >   (In contrast, your 20% mmap protection ratio will keep them all, and
> >   therefore eliminate the extra 41 major faults to restore working set
> >   of zsh etc.)
> 
> I'm surprised this.
> Why your patch don't protect mapped page from streaming io?

I guess you use initlevel=5 and use only terminal, right?
if so, dropping some graphics component makes sense.


> 
> I strongly hope reproduce myself, please teach me reproduce way.




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