bugfindutils - Bugs: bug #32447, Wishlist: fadvise()

 
 

bug #32447: Wishlist: fadvise()

Submitted by:  Alan Brown <stoatwblr>
Submitted on:  Sun 13 Feb 2011 03:38:16 AM UTC  
 
Category: findSeverity: 1 - Wish
Item Group: NoneStatus: None
Privacy: PublicAssigned to: None
Originator Name: Alan BrownOpen/Closed: Open
Release: NoneFixed Release: None

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Tue 24 Sep 2013 10:14:05 PM UTC, comment #5:

Alan, how did you measure the page cache poisoning?

James Youngman <jay>
Project Administrator
Sat 14 May 2011 11:47:19 PM UTC, comment #4:

I see that there's no mention of this request on the gnulib mailing list by Alan yet and no further comment from Alan here. Alan, are you still thinking about this, or are you planning to bring this topic up with the gnulib developers?

James Youngman <jay>
Project Administrator
Sat 02 Apr 2011 05:09:41 PM UTC, comment #3:

It looks to me as if, in order to do this, you would need to update the implementation of opendirat() in gnulib's file lib/fts.c.

Unfortunately, it's not a given that fts() will always need to be restrained in terms of its effect on the page cache. So, I don't know what the developers will say. But, best to start by asking them at bug-gnulib@gnu.org.

James Youngman <jay>
Project Administrator
Tue 15 Feb 2011 04:28:35 PM UTC, comment #2:

Yes, I know it's a no-op, but POSIX_FADV_NONEED is not.

Alan Brown <stoatwblr>
Tue 15 Feb 2011 11:48:58 AM UTC, comment #1:

Hmm. The stuff filling the page cache would be inodes and data read from directories. I suspect that posix_fadvise(2) will not help much here.

(BTW, in Linux the POSIX_FADV_NOREUSE code is currently a no-op.)

Chris(topher) Chittleborough <cchittleborough>
Sun 13 Feb 2011 03:38:16 AM UTC, original submission:

I've discovered that find is causing pagecache poisoning on systems with large filesystems (millions of files).

This can probably be mitigated by using fadvise() to tell the OS that files/directory data doesn't need to be cached.

As far as I can tell it isn't used in any release version of find.

Can the devs look at incorporating this please?

Alan Brown <stoatwblr>

 

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Carbon-Copy List
  • -unavailable- added by jay (Posted a comment)
  • -unavailable- added by cchittleborough (Posted a comment)
  • -unavailable- added by stoatwblr (Submitted the item)
  • -unavailable- added by stoatwblr (findutils - fadvise)
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    Follow 4 latest changes.

    Date Changed By Updated Field Previous Value => Replaced By
    Sat 02 Apr 2011 05:09:40 PM UTCjaySeverity3 - Normal=>1 - Wish
    Tue 15 Feb 2011 11:51:30 AM UTCcchittleboroughCarbon-CopyRemoved cchittleborough=>-
    Tue 15 Feb 2011 11:48:58 AM UTCcchittleboroughCarbon-Copy-=>Added cchittleborough
    Sun 13 Feb 2011 03:38:16 AM UTCstoatwblrCarbon-Copy-=>Added -unavailable-

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