Re: [rfc] lockless pagecache

From: Nick Piggin
Date: Mon Jun 27 2005 - 19:35:02 EST


Benjamin LaHaise wrote:
On Mon, Jun 27, 2005 at 06:02:15PM +1000, Nick Piggin wrote:

However I think for Oracle and others that use shared memory like
this, they are probably not doing linear access, so that would be a
net loss. I'm not completely sure (I don't have access to real loads
at the moment), but I would have thought those guys would have looked
into fault ahead if it were a possibility.


Shared memory overhead doesn't show up on any of the database benchmarks I've seen, as they tend to use huge pages that are locked in memory, and thus don't tend to access the page cache at all after ramp up.


To be quite honest I don't have any real workloads here that stress
it, however I was told that it is a problem for oracle database. If
there is anyone else who has problems then I'd be interested to hear
them as well.

--
SUSE Labs, Novell Inc.

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