Re: [PATCH] mm/filemap.c: unconditionally call mark_page_accessed

On Thu, 15 Mar 2007 22:49:23 +0100
Andrea Arcangeli <andrea@xxxxxxx> wrote:

On Thu, Mar 15, 2007 at 11:07:35AM -0800, Andrew Morton wrote:
On Thu, 15 Mar 2007 01:22:45 -0400 (EDT) Ashif Harji <asharji@xxxxxxxxxxxxxxx> wrote:
I still think the simple fix of removing the
condition is the best approach, but I'm certainly open to alternatives.

Yes, the problem of falsely activating pages when the file is read in small
hunks is worse than the problem which your patch fixes.

Really? I would have expected all performance sensitive apps to read
in >=PAGE_SIZE chunks. And if they don't because they split their
dataset in blocks (like some database), it may not be so wrong to
activate those pages that have two "hot" blocks more aggressively than
those pages with a single hot block.

But the problem which is being fixed here is really obscure: an application
repeatedly reading the first page and only the first page of a file, always
via the same fd.

I'd expect that the sub-page-size read scenarion happens heaps more often
than that, especially when dealing with larger PAGE_SIZEs.


-
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at http://vger.kernel.org/majordomo-info.html
Please read the FAQ at http://www.tux.org/lkml/

Relevant Pages

  • Re: [PATCH] mm/filemap.c: unconditionally call mark_page_accessed
    ... I still think the simple fix of removing the ... the problem of falsely activating pages when the file is read in small ... in>=PAGE_SIZE chunks. ...
    (Linux-Kernel)
  • Re: Removing .tmp_versions considered harmful
    ... as MadWifi) are now compiled with spurious warnings about unresolved ... to fix all that mess. ... I'm aware that 2-4 support complicates things a little but if people ... Can we settle on removing only *.mod files ...
    (Linux-Kernel)
  • Re: open(2) says O_DIRECT works on 512 byte boundries?
    ... Andrea Arcangeli wrote: ... If you also run into this final fix is attached below. ... Why TestSetLockPage() is necessary? ... reason of the slowdown (the slowdown were the false positives ...
    (Linux-Kernel)
  • Re: [PATCH 2.6.23-rc6 Resending] NETWORKING : Edge Triggered EPOLLOUT events get missed for TCP
    ... Infact I thought a lot about that before deciding on this fix. ... How much effect will removing the check have (if we cannot ... IMHO for a "fast sender" the SOCK_NOSPACE check will ... before the prev data is drained out. ...
    (Linux-Kernel)
  • Re: power point & mpegs
    ... Yeah you have some Movie Software like Muvee autoproducer or something on ... The easiest way to fix the problem is by removing the software...if you dont ... These are the mainconcept mpeg filters/decoders which are installed by Muvee ...
    (microsoft.public.powerpoint)