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2.6 swapping behavior2.6 swapping behaviorPosted May 7, 2004 7:59 UTC (Fri) by njhurst (guest, #6022)In reply to: 2.6 swapping behavior by iabervon Parent article: 2.6 swapping behavior I don't understand why updatedb needs so much cache memory? Surely it only needs to keep a stack of inodes from root to the current point in the filesystem in memory. Once it has looked at a file that file's memory should be returned to the pool immediately. I don't know how to force the kernel to do this though. (This is obviously updatedb specific information, but maybe it would be easier to fix updatedb than everything else?)
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2.6 swapping behavior Posted May 7, 2004 21:53 UTC (Fri) by addw (guest, #1771) [Link] Trouble is that the kernel doesn't know that the updatedb is not going to look at those files ever again (well, 'till it runs again tomorrow). But the blocks from the file system are left in memory on the grounds that something recently used it likely to be used again in the near future.Simple prediction doesn't always work.
2.6 swapping behavior Posted May 13, 2004 0:19 UTC (Thu) by njhurst (guest, #6022) [Link] I agree, my point is just that maybe some thought could be put into making updatedb more well behaved, rather than trying to get that behaviour directly out of the kernel?I think it is allowable to have user space programs try to optimise their behaviour with the kernel :)
2.6 swapping behavior Posted May 14, 2004 11:17 UTC (Fri) by forthy (guest, #1525) [Link] IMHO the initial priority of a just-allocated or just-loaded buffer is toohigh. That's why memory hogs (which claim a page once and never look at it again) swap out everything else in Linux, and updatedb also does the same thing. The pages of OpenOffice, which have been used and reused all day long over and over again have lower priority for the kernel than a newly allocated use-once page. But as long as kernel developer stick their thumbs in their ears and sing "lalala", this won't change. Another note: updatedb *only* reads the names of a file system. Well, it also checks if a name is a directory, and that forces it to read the entire inode. The real problem here is that updatedb tries to solve something the file system should do itself (especially if you think of it like Hans Reiser does). Why is it impossible for the file system to keep the file names in a database like updatedb, and answer queries like locate directly? Hint: BeOS did something like that.
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