Messages in this thread | | | Date | Thu, 14 Oct 2004 10:53:00 +1000 | From | Nathan Scott <> | Subject | Re: Page cache write performance issue |
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On Wed, Oct 13, 2004 at 01:39:41AM -0700, Andrew Morton wrote: > Nick Piggin <piggin@cyberone.com.au> wrote: > > > > Andrew probably has better ideas. > > uh, is this an ia32 highmem box?
Yep, it is.
> If so, you've hit the VM sour spot. > ... > Basically, *any* other config is fine. 896MB and below, 1.5GB and above.
I just tried switching CONFIG_HIGHMEM off, and so running the machine with 512MB; then adjusted the test to write 256M into the page cache, again in 1K sequential chunks. A similar mis- behaviour happens, though the numbers are slightly better (up from ~4 to ~6.5MB/sec). Both ext2 and xfs see this. When I drop the file size down to 128M with this kernel, I see good results again (as we'd expect).
I'm being pulled onto other issues atm, but in the background I could try reverting specific changesets if you guys can suggest anything in particular that might be triggering this?
thanks!
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