Messages in this thread | | | Date | Mon, 08 Sep 2008 08:17:03 -0700 | From | Mike Travis <> | Subject | Re: [RFC 00/13] smp: reduce stack requirements for genapic send_IPI_mask functions |
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Ingo Molnar wrote: > * Mike Travis <travis@sgi.com> wrote: > >> [Note: all these changes require some more testing but I wanted to >> solicit comments before then, hence the "RFC" in the subject line. >> -thanks! Mike] > > these changes are certainly looking very nice. > > They do interact with a ton of high-flux topics in -tip, so i'd prefer > to start integrating/testing this straight away (today-ish), before the > target moves yet again. Are there any showstoppers that speak against > that? > > The plan would be to not keep this in a single topic but to spread them > into their closest topic (tip/x86/x2apic, tip/irq/sparseirq etc.) - are > there any cross-topic dependencies to be careful about? Most of the > commits seem to be standalone. The debug patch would go into > tip/cpus4096. > > And more generally: how far away are we from being able to introduce > struct cpumask and hide its implementation from most .c files? That > would be rather efficient in preventing it from being put on the stack > spuriously in one of the 30+ thousand Linux kernel source code files. > Just like we hide the true structure of things like 'struct kmem_cache' > and force them to always be used as pointers. > > Ingo
What I'll do is resubmit the changes that have nothing to do with cpumask_ptr's first as they are mostly just "cleaning up extraneous temp cpumask variables". Then I'll try the redefine of cpumask_t to see what kind of hornet's nest is opened up.
What do you think of a pool of temp cpumask_t's? That way, they could be made available early (before kmalloc is available). An atomic op could be used for reservation which when the zero-based percpu variables finally get completed, become very low cost.
Thanks, Mike
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