Messages in this thread |  | | Date | Wed, 13 Oct 2004 17:23:53 +1000 | From | Nathan Scott <> | Subject | Re: Page cache write performance issue |
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On Wed, Oct 13, 2004 at 12:02:06AM -0700, Andrew Morton wrote: > > Well something else if fishy: how can you possibly achieve only 4MB/sec?
These are 1K writes too remember, so it feels a bit like we write 'em out one at a time, sync (though no O_SYNC, or fsync, or such involved here). This is on an i686, so 4K pages, and using 4K filesystem blocksizes (both xfs and ext2).
And now that you mention, yes, this is multiple times below the direct IO numbers too (which on this box are ~30MB/sec for direct blkdev writes, IIRC, & XFS has similar numbers).
> Using floppy disks or something?
Heh, uh, no. (and no, not "pencils" either ;)
> Does the same happen on ext2?
Yes.
> It's exactly a 500MB write on a 1000MB machine, yes?
Thats correct.
No slab/page/.. debug options enabled either - its the same .config that was performing ~10x better on 2.6.8. I also verified that it wasn't any of the XFS changes either (they wouldn't have affected ext2 anyway, of course) - the same XFS code backported to 2.6.8 performs fine also.
cheers.
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