On Thu, 2014-09-18 at 18:26 +1000, Michael Neuling wrote: > From: Ian Munsie <imun...@au1.ibm.com> > > Currently msi_bitmap_alloc_hwirqs() will round up any IRQ allocation requests > to the nearest power of 2. eg. ask for 5 IRQs and you'll get 8. This wastes > a > lot of IRQs which can be a scarce resource. > > For cxl we can require multiple IRQs for every contexts that is attached to > the > accelerator. For AFU directed accelerators, there may be 1000s of contexts > attached, hence we can easily run out of IRQs, especially if we are needlessly > wasting them. > > This changes the msi_bitmap_alloc_hwirqs() to allocate only the required > number > of IRQs, hence avoiding this wastage. > > Signed-off-by: Ian Munsie <imun...@au1.ibm.com> > Signed-off-by: Michael Neuling <mi...@neuling.org> > --- > arch/powerpc/sysdev/msi_bitmap.c | 18 +++++++++++++----- > 1 file changed, 13 insertions(+), 5 deletions(-)
This conflicts with (and partially duplicates) http://patchwork.ozlabs.org/patch/381892/ which I have in my tree. How should we handle it? Laurentiu, from looking at the overlap between patches I see a problem with your existing patch, regarding the out-of-irqs path and msi_bitmap_free_hwirqs(), so one way or another that needs to get fixed soon. -Scott > diff --git a/arch/powerpc/sysdev/msi_bitmap.c > b/arch/powerpc/sysdev/msi_bitmap.c > index 2ff6302..e001559 100644 > --- a/arch/powerpc/sysdev/msi_bitmap.c > +++ b/arch/powerpc/sysdev/msi_bitmap.c > @@ -24,28 +24,36 @@ int msi_bitmap_alloc_hwirqs(struct msi_bitmap *bmp, int > num) > * This is fast, but stricter than we need. We might want to add > * a fallback routine which does a linear search with no alignment. > */ > - offset = bitmap_find_free_region(bmp->bitmap, bmp->irq_count, order); > + offset = bitmap_find_next_zero_area(bmp->bitmap, bmp->irq_count, 0, > + num, (1 << order) - 1); > + if (offset > bmp->irq_count) > + goto err; > + bitmap_set(bmp->bitmap, offset, num); > spin_unlock_irqrestore(&bmp->lock, flags); > > pr_debug("msi_bitmap: allocated 0x%x (2^%d) at offset 0x%x\n", > num, order, offset); > > return offset; > +err: > + spin_unlock_irqrestore(&bmp->lock, flags); > + return -ENOMEM; > } > +EXPORT_SYMBOL(msi_bitmap_alloc_hwirqs); > > void msi_bitmap_free_hwirqs(struct msi_bitmap *bmp, unsigned int offset, > unsigned int num) > { > unsigned long flags; > - int order = get_count_order(num); > > - pr_debug("msi_bitmap: freeing 0x%x (2^%d) at offset 0x%x\n", > - num, order, offset); > + pr_debug("msi_bitmap: freeing 0x%x at offset 0x%x\n", > + num, offset); > > spin_lock_irqsave(&bmp->lock, flags); > - bitmap_release_region(bmp->bitmap, offset, order); > + bitmap_clear(bmp->bitmap, offset, num); > spin_unlock_irqrestore(&bmp->lock, flags); > } > +EXPORT_SYMBOL(msi_bitmap_free_hwirqs); > > void msi_bitmap_reserve_hwirq(struct msi_bitmap *bmp, unsigned int hwirq) > { -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
