On Tue, 2006-03-07 at 16:39, Andi Kleen wrote:
> On Wednesday 01 March 2006 02:10, Zou Nan hai wrote:
> > on X86_64, swiotlb buffer is allocated in mem_init, after memmap and vfs cache allocation.
> >
> > On platforms with huge physical memory,
> > large memmap and vfs cache may eat up all usable system memory
> > under 4G.
> >
> > Move swiotlb_init early before memmap is allocated can
> > solve this issue.
> >
> > Signed-off-by: Zou Nan hai <[email protected]>
>
>
> I came up with a simpler change now that should fix the problem too.
> It just try to move the memmap to the end of the node. I don't have a system
> big enough to test the original problem though.
>
> It should be fairly safe because if the allocation fails we just fallback
> to the normal old way of allocating it near the beginning.
>
> Try to allocate node memmap near the end of node
>
> This fixes problems with very large nodes (over 128GB) filling up all of
> the first 4GB with their mem_map and not leaving enough
> space for the swiotlb.
>
>
> Signed-off-by: Andi Kleen <[email protected]>
>
> ---
> arch/x86_64/mm/numa.c | 12 +++++++++++-
> include/linux/bootmem.h | 3 +++
> mm/bootmem.c | 2 +-
> 3 files changed, 15 insertions(+), 2 deletions(-)
>
> Index: linux/arch/x86_64/mm/numa.c
> ===================================================================
> --- linux.orig/arch/x86_64/mm/numa.c
> +++ linux/arch/x86_64/mm/numa.c
> @@ -172,7 +172,7 @@ void __init setup_node_bootmem(int nodei
> /* Initialize final allocator for a zone */
> void __init setup_node_zones(int nodeid)
> {
> - unsigned long start_pfn, end_pfn;
> + unsigned long start_pfn, end_pfn, memmapsize, limit;
> unsigned long zones[MAX_NR_ZONES];
> unsigned long holes[MAX_NR_ZONES];
>
> @@ -182,6 +182,16 @@ void __init setup_node_zones(int nodeid)
> Dprintk(KERN_INFO "Setting up node %d %lx-%lx\n",
> nodeid, start_pfn, end_pfn);
>
> + /* Try to allocate mem_map at end to not fill up precious <4GB
> + memory. */
> + memmapsize = sizeof(struct page) * (end_pfn-start_pfn);
> + limit = end_pfn << PAGE_SHIFT;
> + NODE_DATA(nodeid)->node_mem_map =
> + __alloc_bootmem_core(NODE_DATA(nodeid)->bdata,
> + memmapsize, SMP_CACHE_BYTES,
> + limit,
> + round_down(limit - memmapsize, PAGE_SIZE));
> +
, round_down(limit - memmapsize, PAGE_SIZE), limit);?
Zou Nan hai
-
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