Messages in this thread |  | | Date | Tue, 6 Nov 2001 14:55:53 -0200 (BRST) | From | Marcelo Tosatti <> | Subject | Re: Using %cr2 to reference "current" |
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On Tue, 6 Nov 2001, Alan Cox wrote:
> > "get_current" interrupt safe (ie switching tasks is totally atomic, as > > it's the one single "movl ..,%esp" instruction that does the real switch > > as far as the kernel is concerned). > > > > It does require using an order-2 allocation, which the current VM will > > allow anyway, but which is obviously nastier than an order-1. > > I've seen boxes dead in the water from 8K NFS (ie 16K order-2 allocations), > let alone the huge memory hit. Michael's rtlinux approach looks even more > interesting and I may have to play with that (using the TSS to ident the > cpu)
Btw, I also want to see what intense "for-optimization" high-order allocators are going to do to the current VM.
Think about the possible intensive pressure (and CPU wasted) caused by, for example, SCSI code which _always_ tries to do 1-order allocations (or bigger?) to allocate scatter/gather tables. We want those allocations to fail to 0-order allocations instead looping madly inside the VM freeing routines.
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