On Wed, Jul 25, 2018 at 05:02:59PM -0600, Jon Derrick wrote: > Currently, a hotplug bridge will be given hpmemsize additional memory if > available, in order to satisfy any future hotplug allocation > requirements. > > These calculations don't consider the current memory size of the hotplug > bridge/slot, so hotplug bridges/slots which have downstream devices will > get their current allocation in addition to the hpmemsize value. > > This makes for possibly undesirable results with a mix of unoccupied and > occupied slots (ex, with hpmemsize=2M): > > 02:03.0 PCI bridge: <-- Occupied > Memory behind bridge: d6200000-d64fffff [size=3M] > 02:04.0 PCI bridge: <-- Unoccupied > Memory behind bridge: d6500000-d66fffff [size=2M] > > This change considers the current allocation size when using the > hpmemsize parameter to make the reservations predictable for the mix of > unoccupied and occupied slots: > > 02:03.0 PCI bridge: <-- Occupied > Memory behind bridge: d6200000-d63fffff [size=2M] > 02:04.0 PCI bridge: <-- Unoccupied > Memory behind bridge: d6400000-d65fffff [size=2M] The I/O sizing code (pbus_size_io() and calculate_iosize()) is essentially identical to the mem sizing code you're updating. I assume the same considerations would apply there? If not, please include a note in the changelog about why you changed the mem code but not the I/O code. > Signed-off-by: Jon Derrick <jonathan.derrick@xxxxxxxxx> > --- > Original RFC here: > https://patchwork.ozlabs.org/patch/945374/ > > I split this bit out from the RFC while awaiting the pci string handling > enhancements to handle per-device settings > > Changed from RFC is a simpler algo > > drivers/pci/setup-bus.c | 13 ++++++------- > 1 file changed, 6 insertions(+), 7 deletions(-) > > diff --git a/drivers/pci/setup-bus.c b/drivers/pci/setup-bus.c > index 79b1824..5ae39e6 100644 > --- a/drivers/pci/setup-bus.c > +++ b/drivers/pci/setup-bus.c > @@ -831,7 +831,8 @@ static resource_size_t calculate_iosize(resource_size_t size, > > static resource_size_t calculate_memsize(resource_size_t size, > resource_size_t min_size, > - resource_size_t size1, > + resource_size_t add_size, > + resource_size_t children_add_size, > resource_size_t old_size, > resource_size_t align) > { > @@ -841,7 +842,7 @@ static resource_size_t calculate_memsize(resource_size_t size, > old_size = 0; > if (size < old_size) > size = old_size; > - size = ALIGN(size + size1, align); > + size = ALIGN(max(size, add_size) + children_add_size, align); > return size; > } > > @@ -1079,12 +1080,10 @@ static int pbus_size_mem(struct pci_bus *bus, unsigned long mask, > > min_align = calculate_mem_align(aligns, max_order); > min_align = max(min_align, window_alignment(bus, b_res->flags)); > - size0 = calculate_memsize(size, min_size, 0, resource_size(b_res), min_align); > + size0 = calculate_memsize(size, min_size, 0, 0, resource_size(b_res), min_align); > add_align = max(min_align, add_align); > - if (children_add_size > add_size) > - add_size = children_add_size; > - size1 = (!realloc_head || (realloc_head && !add_size)) ? size0 : > - calculate_memsize(size, min_size, add_size, > + size1 = (!realloc_head || (realloc_head && !add_size && !children_add_size)) ? size0 : > + calculate_memsize(size, min_size, add_size, children_add_size, > resource_size(b_res), add_align); > if (!size0 && !size1) { > if (b_res->start || b_res->end) > -- > 1.8.3.1 >
