Re: [PATCH] X86: Change the default value of nr_irqs from 32 to NR_IRQs
From: Alex Nixon
Date: Wed Aug 20 2008 - 19:24:10 EST
Alex Nixon wrote:
Yinghai Lu wrote:
when !CONFIG_HAVE_SPARSE_IRQ, with dyn_array, could allocate irq_desc
and etc as less as possible.
when CONFIG_HAVE_SPARESE_IRQ, no actually meaning for nr_irqs.
YH
So I believe the only case this affects is !CONFIG_HAVE_SPARSE_IRQ
The worry is that with CONFIG_HAVE_DYN_ARRAY we may waste memory by
pre-allocating more irq_descs than may be necessary (NR_IRQs vs 32)?
With !CONFIG_HAVE_DYN_ARRAY however, a static array of size NR_IRQS is
allocated instead - so doesn't defaulting nr_irqs back to NR_IRQS just
revert to the old behaviour (with the exception of the irq_descs being
allocated in pre_alloc_dyn_array instead)?
- Alex
Sorry to pester you Yinghai, but I'd like to get a patch for this out
one way or another as Xen is _completely_ unusable with 5 or more VCPUs.
Can you explain more clearly what the problem with the patch is?
I have a different patch set which solves the problem by adding in a pv
hook for probe_nr_irqs, but it's by far less clean.
Or alternatively, we could revert your patch b2e5f326bb
Cheers,
- Alex
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