Messages in this thread | | | Date | Wed, 16 Jan 2002 18:31:55 -0200 (BRST) | From | Marcelo Tosatti <> | Subject | Re: [patch][rfc][rft] vm throughput 2.4.2-ac4 |
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On Wed, 28 Feb 2001, Mike Galbraith wrote:
> On Wed, 28 Feb 2001, Marcelo Tosatti wrote: > > > On Wed, 28 Feb 2001, Mike Galbraith wrote: > > > > > > > Have you tried to use SWAP_SHIFT as 4 instead of 5 on a stock 2.4.2-ac5 to > > > > > see if the system still swaps out too much? > > > > > > > > Not yet, but will do. > > > > But what about swapping behaviour? > > > > It still swaps too much? > > Yes. > > (returning to study mode)
Ok, I'm stupid. Changing SWAP_SHIFT will just balance the nr of tasks and the per-task nr of scanned pte's, but the not (roughly) the total nr of ptes scanned. I thought it would decrease the number of scanned ptes from 3% (which the current in -ac code does) to 0.3% (which Linus tree does) of the total ptes.
The problem seems to be multiple users calling swap_out() with 3% of ptes being scanned. This will unmap ptes way too heavily for common workloads.
Its magic number tuning.. but nothing better can be done for 2.4, I think.
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