Messages in this thread | | | Date | Mon, 12 Jul 1999 17:48:36 +0200 | From | Jamie Lokier <> | Subject | Re: [RFC] - Some notions that I would like comments on |
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Stefan Monnier wrote: > > This involves finding parallelism in the kernel and getting an > > otherwise idle processor to handle one of the parallel chunks of > > work. > > Hopeless. The cost of inter-CPU communication is way too high to try > to share such fine-grained tasks.
I reckon a spare CPU could happily
- pre-zero some pages, preferably spread over the range of page colours. - move pages around to make space for multi-page allocations. - checksum pages to find duplicates and merge them in the background
> > Compressive paging > > Before writing a page out to swap, compress it.
> > IPC through page remapping > > Slow. Only worth it if the message is big enough (last time I heard, the > cut-over point was around 8KB).
Uusually the overhead of TLB flushes or the need for inter-CPU TLB flush messages is given as the reason.
But there are cases when those can be shown to be not necessary. Like when you read a page, and the pte is not marked "accessed" yet. No TLB flush required.
Similarly when you write a page and its marked "dirty" but not "accessed" -- I'm not sure if this combination (written but not read) is flagged by CPUs though.
-- Jamie
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