What is the active page in Linux kernel, so inactive? - Linux

This is a discussion on What is the active page in Linux kernel, so inactive? - Linux ; I am quite confusing about the concept that Linux usage of the term active and inactive pages. Some book tells me active pages is the 'working set' in system, but what is the 'working set'? There is a page cache ...

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Thread: What is the active page in Linux kernel, so inactive?

  1. What is the active page in Linux kernel, so inactive?

    I am quite confusing about the concept that Linux usage of the term
    active and inactive pages. Some book tells me active pages is the
    'working set' in system, but what is the 'working set'? There is a
    page cache system in the system, and when a page is freed when not
    needed by some way, the page will first considered be added to the
    page cache. Once some stuff need more pages, it also get it from page
    cache.

    So it is easy to understand that there is two list in the page cache,
    one for 'used' pages, that is, the page actually used by some one. And
    the other one is 'unused', that is, unused by any one but is still
    cached.

    But I doubt whether the 'used' and 'unused' correspond to active and
    inactive correctly? If I am right, when the system memory is tight,
    the pages in the active list will be swapped out and the pages will be
    added to the inactive list? Or the pages that has swapped out go
    directly to the buddy allocator?

    Thanks in advance.

    abai


  2. Re: What is the active page in Linux kernel, so inactive?

    Bin Chen wrote:
    > I am quite confusing about the concept that Linux usage of the term
    > active and inactive pages. Some book tells me active pages is the
    > 'working set' in system, but what is the 'working set'? There is a
    > page cache system in the system, and when a page is freed when not
    > needed by some way, the page will first considered be added to the
    > page cache. Once some stuff need more pages, it also get it from page
    > cache.
    >
    > So it is easy to understand that there is two list in the page cache,
    > one for 'used' pages, that is, the page actually used by some one. And
    > the other one is 'unused', that is, unused by any one but is still
    > cached.
    >
    > But I doubt whether the 'used' and 'unused' correspond to active and
    > inactive correctly? If I am right, when the system memory is tight,
    > the pages in the active list will be swapped out and the pages will be
    > added to the inactive list? Or the pages that has swapped out go
    > directly to the buddy allocator?



    Get a textbook that handles virtual memory management.

    You're asking for the textbook basics.

    --

    Tauno Voipio
    tauno voipio (at) iki fi

  3. Re: What is the active page in Linux kernel, so inactive?

    On 3月31日, 上午2时18分, Tauno Voipio wrote:
    > Bin Chen wrote:
    > > I am quite confusing about the concept that Linux usage of the term
    > > active and inactive pages. Some book tells me active pages is the
    > > 'working set' in system, but what is the 'working set'? There is a
    > > page cache system in the system, and when a page is freed when not
    > > needed by some way, the page will first considered be added to the
    > > page cache. Once some stuff need more pages, it also get it from page
    > > cache.

    >
    > > So it is easy to understand that there is two list in the page cache,
    > > one for 'used' pages, that is, the page actually used by some one. And
    > > the other one is 'unused', that is, unused by any one but is still
    > > cached.

    >
    > > But I doubt whether the 'used' and 'unused' correspond to active and
    > > inactive correctly? If I am right, when the system memory is tight,
    > > the pages in the active list will be swapped out and the pages will be
    > > added to the inactive list? Or the pages that has swapped out go
    > > directly to the buddy allocator?

    >
    > Get a textbook that handles virtual memory management.
    >
    > You're asking for the textbook basics.

    Your reply seems very useless. If what I am asking is really basics,
    you can point me to a real book and the part describes this in detail.
    Otherwise, you can type a simple 'yes' or 'no' to my question, this at
    least give me a hint.
    And, after I google this, I found a mail in LKML discuss this too.
    http://kerneltrap.org/node/7608

    The author of the page cache says it uses two list to avoid cache
    pollution.



  4. Re: What is the active page in Linux kernel, so inactive?

    In article <1175301465.542173.189030@r56g2000hsd.googlegroups. com>,
    "Bin Chen" wrote:

    > On 3月31日, 上午2时18分, Tauno Voipio wrote:
    > > Bin Chen wrote:
    > > > I am quite confusing about the concept that Linux usage of the term
    > > > active and inactive pages. Some book tells me active pages is the
    > > > 'working set' in system, but what is the 'working set'? There is a
    > > > page cache system in the system, and when a page is freed when not
    > > > needed by some way, the page will first considered be added to the
    > > > page cache. Once some stuff need more pages, it also get it from page
    > > > cache.

    > >
    > > > So it is easy to understand that there is two list in the page cache,
    > > > one for 'used' pages, that is, the page actually used by some one. And
    > > > the other one is 'unused', that is, unused by any one but is still
    > > > cached.

    > >
    > > > But I doubt whether the 'used' and 'unused' correspond to active and
    > > > inactive correctly? If I am right, when the system memory is tight,
    > > > the pages in the active list will be swapped out and the pages will be
    > > > added to the inactive list? Or the pages that has swapped out go
    > > > directly to the buddy allocator?

    > >
    > > Get a textbook that handles virtual memory management.
    > >
    > > You're asking for the textbook basics.

    > Your reply seems very useless. If what I am asking is really basics,
    > you can point me to a real book and the part describes this in detail.


    A good textbook on this is "Operating Systems" by Deitel, Deitel, and
    Choffnes. It explains almost all aspects of modern OS design, and has
    appendixes explaining how these are implemented in Windows XP and Linux.

    --
    Barry Margolin, barmar@alum.mit.edu
    Arlington, MA
    *** PLEASE post questions in newsgroups, not directly to me ***
    *** PLEASE don't copy me on replies, I'll read them in the group ***

  5. Re: What is the active page in Linux kernel, so inactive?

    In article <1175301465.542173.189030@r56g2000hsd.googlegroups. com>,
    Bin Chen wrote:

    >Your reply seems very useless.


    Do you think you are owed more?


  6. Re: What is the active page in Linux kernel, so inactive?

    Bin Chen wrote:
    > On 3月31日, 上午2时18分, Tauno Voipio wrote:
    >
    >>Bin Chen wrote:
    >>
    >>>I am quite confusing about the concept that Linux usage of the term
    >>>active and inactive pages. Some book tells me active pages is the
    >>>'working set' in system, but what is the 'working set'? There is a
    >>>page cache system in the system, and when a page is freed when not
    >>>needed by some way, the page will first considered be added to the
    >>>page cache. Once some stuff need more pages, it also get it from page
    >>>cache.

    >>
    >>>So it is easy to understand that there is two list in the page cache,
    >>>one for 'used' pages, that is, the page actually used by some one. And
    >>>the other one is 'unused', that is, unused by any one but is still
    >>>cached.

    >>
    >>>But I doubt whether the 'used' and 'unused' correspond to active and
    >>>inactive correctly? If I am right, when the system memory is tight,
    >>>the pages in the active list will be swapped out and the pages will be
    >>>added to the inactive list? Or the pages that has swapped out go
    >>>directly to the buddy allocator?

    >>
    >>Get a textbook that handles virtual memory management.
    >>
    >>You're asking for the textbook basics.

    >
    > Your reply seems very useless. If what I am asking is really basics,
    > you can point me to a real book and the part describes this in detail.
    > Otherwise, you can type a simple 'yes' or 'no' to my question, this at
    > least give me a hint.
    > And, after I google this, I found a mail in LKML discuss this too.
    > http://kerneltrap.org/node/7608
    >
    > The author of the page cache says it uses two list to avoid cache
    > pollution.



    It seems that you're in need for the basics of O/S programming.

    You could start with e.g. Understanding the Linux Kernel, published
    by O'Reilly.

    --

    Tauno Voipio
    tauno voipio (at) iki fi

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