Messages in this thread | | | Subject | Re: [PATCH 2.5.43-mm2] New shared page table patch | From | (Eric W. Biederman) | Date | 19 Oct 2002 22:20:47 -0600 |
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Dave McCracken <dmccr@us.ibm.com> writes:
> This patch isn't primarily a performance patch. It does help for some > things, notably the fork/exec/exit cases mentioned above. But its primary > goal is to reduce the amount of memory wasted in page tables mapping the > same pages into multiple processes. We have seen an application that > consumed on the order of 10 GB of page tables to map a single shared memory > chunk across hundreds of processes. Shared page tables would eliminate > this overhead.
Have you considered putting a fixed upper bound on the number of pages tables a page can be mapped into? This would result in the same amount of memory reduction, with what should be very little complexity.
I admit there would be a few more demand paging hits, but they should be controllable. And I suspect their performance impact would be lost in the noise.
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