On Sat, Mar 19, 2005 at 08:26:45PM +0100, Andi Kleen wrote:
On Fri, Mar 18, 2005 at 03:23:44PM -0600, Matt Domsch wrote:
For review and comment.
On x86_64 systems with no IOMMU and with 4GB RAM (in fact, whenever
there are any pages mapped above 4GB), pci_alloc_consistent() falls
back to using ZONE_DMA for all allocations, even if the device's
dma_mask could have supported using memory from other zones. Problems
can be seen when other ZONE_DMA users (SWIOTLB, scsi_malloc()) consume
all of ZONE_DMA, leaving none left for pci_alloc_consistent() use.
Patch below makes pci_alloc_consistent() for the nommu case (EM64T
processors) match the 2.6 implementation of dma_alloc_coherent(), with
the exception that this continues to use GFP_ATOMIC.
You fixed the wrong code. The pci-nommu code is only used
when IOMMU is disabled in the Kconfig. But most kernels have
it enabled. You would need to change it in pci-gart.c too.
OK, then how's this for review? Compiles clean, can't test it myself
for a few days.
--
Matt Domsch
Software Architect
Dell Linux Solutions linux.dell.com www.dell.com/linux
Linux on Dell mailing lists @ http://lists.us.dell.com
= arch/x86_64/kernel/pci-gart.c 1.12 vs edited =
--- 1.12/arch/x86_64/kernel/pci-gart.c 2004-06-03 05:29:36 -05:00
+++ edited/arch/x86_64/kernel/pci-gart.c2005-03-19 15:56:34 -06:00
@@ -154,27 +154,37 @@ void *pci_alloc_consistent(struct pci_de
int gfp = GFP_ATOMIC;
int i;
unsigned long iommu_page;
+ dma_addr_t dma_mask;
- if (hwdev == NULL || hwdev-dma_mask 0x || no_iommu)
+ if (hwdev == NULL || hwdev-dma_mask 0x)
gfp |= GFP_DMA;
+ dma_mask = hwdev ? hwdev-dma_mask : 0xULL;
+ if (dma_mask == 0)
+ dma_mask = 0xULL;
+
/*
-* First try to allocate continuous and use directly if already
-* in lowmem.
+* First try to allocate continuous and use directly if
+* our device supports it
*/
size = round_up(size, PAGE_SIZE);
+ again:
memory = (void *)__get_free_pages(gfp, get_order(size));
if (memory == NULL) {
return NULL;
} else {
- int high = 0, mmu;
- if (((unsigned long)virt_to_bus(memory) + size) 0xUL)
- high = 1;
- mmu = high;
+ int high = (((unsigned long)virt_to_bus(memory) + size)
~dma_mask) != 0;
+ int mmu = high;
if (force_mmu !(gfp GFP_DMA))
mmu = 1;
if (no_iommu) {
- if (high) goto error;
+ if (high (gfp GFP_DMA))
+ goto error;
+ if (high) {
+ free_pages((unsigned long)memory,
get_order(size));
+ gfp |= GFP_DMA;
+ goto again;
+ }
mmu = 0;
}
memset(memory, 0, size);
-
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