Messages in this thread | | | Date | Thu, 17 Dec 2009 08:39:58 -0500 | From | Mathieu Desnoyers <> | Subject | Re: [this_cpu_xx V7 0/8] Per cpu atomics in core allocators and cleanup |
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* Tejun Heo (tj@kernel.org) wrote: > Hello, > > On 12/16/2009 10:40 AM, Mathieu Desnoyers wrote: > > Nope, there is the same number of sub-buffers for each per-cpu buffer. > > I just want to see if supplementary indirections are allowed after > > dereferencing the per-cpu pointer ? > > Hmmm... you can store percpu pointer to a variable. If there are the > same number of commit_count for each cpu, they can be allocated using > percpu allocator and their pointers can be stored, offset and > dereferenced. Would that be enough?
Yes, I think I could allocate, from the channel structure perspective:
- A percpu pointer to the per-cpu buffer structures - A percpu pointer to the per-cpu commit counters.
This should fix my problem. The main change here is that the pointer to the commit counters would not be located in the per-cpu buffer structures anymore.
However, I would need:
this_cpu_cmpxchg(scalar, oldv, newv) (maps to x86 cmpxchg)
this_cpu_add_return(scalar, value) (maps to x86 xadd)
too. Is that a planned addition ?
(while we are at it, we might as will add the xchg instruction, althrough it has an implied LOCK prefix on x86).
Thanks,
Mathieu
> > Thanks. > > -- > tejun
-- Mathieu Desnoyers OpenPGP key fingerprint: 8CD5 52C3 8E3C 4140 715F BA06 3F25 A8FE 3BAE 9A68
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