Messages in this thread | | | Date | Fri, 11 May 2007 10:27:39 +0100 (BST) | From | Hugh Dickins <> | Subject | Re: slub-i386-support.patch |
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On Fri, 11 May 2007, Andrew Morton wrote: > On Fri, 11 May 2007 10:29:30 +0200 Andi Kleen <ak@suse.de> wrote: > > > > I'm guessing (haven't rechecked source) that the cpu_idle() call comes > > > about because the top level pgd of a process gets freed very late in > > > its exit, and after a great flurry of processes have just exited, > > > perhaps there was nothing to free up the accumulation. Though > > > it still strikes me as an odd place to do it. > > > > I always found it odd and probably the wrong place too. > > so... what's the bottom line here, guys? Should we change that patch?
The bottom line... I can see why you're asking for that ;)
I'd say delete the change to arch/i386/kernel/smp.c - contrary to what Christoph says, no other arch buries a check_pgt_cache() call in flush_tlb_mm(), that just seems to be a thinko: i386 has the usual call to it from tlb_finish_mmu() - _that_ is the one which he and David were talking about.
I'm just worried that there might somewhere be a call to flush_tlb_mm() which would now be surprised to be freeing pages: almost certainly not, but why raise that concern? It's just not flush_tlb_mm()'s business.
The cpu_idle() call should stay for now: we're agreed that it's odd, but there's plenty of precedent for it, and it's easier to imagine it serves a real purpose, and shouldn't be removed without replacement.
Bill raised a real concern about unnecessary PAE pgd memory usage, but let's get the patch into -rc1 to enable the wider SLUB testing, before coming back to fix that up. His micro-optimizations can wait.
IMHO Hugh - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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