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    SubjectRe: [PATCH 2/3] vmscan: make mapped executable pages the first class citizen
    On Tue, May 19, 2009 at 12:44:19PM +0800, KOSAKI Motohiro wrote:
    > > > 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.

    No, it's in pure console mode, no X running at all.

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


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