Messages in this thread Patch in this message | | | From | Eric Dumazet <> | Subject | [PATCH] Try to avoid a pessimistic vmalloc() recursion | Date | Mon, 9 Oct 2006 16:47:55 +0200 |
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__vmalloc_area_node() is a litle bit pessimist when allocating space for storing struct page pointers.
When allocating more than 4 MB on ia32, or 2 MB on x86_64, __vmalloc_area_node() has to allocate more than PAGE_SIZE bytes to store pointers to page structs. This means that two TLB translations are needed to access data.
This patch tries a kmalloc() call, then only if this first attempt failed, a vmalloc() is performed. (Later, at vfree() time we chose kfree() or vfree() with a test on flags & VM_VPAGES : no change is needed)
Most of the time, the first kmalloc() should be OK, so we reduce TLB usage.
Signed-off-by: Eric Dumazet <dada1@cosmosbay.com> --- linux-2.6.18/mm/vmalloc.c 2006-10-09 13:58:13.000000000 +0200 +++ linux-2.6.18-ed/mm/vmalloc.c 2006-10-09 14:04:11.000000000 +0200 @@ -426,12 +426,12 @@ array_size = (nr_pages * sizeof(struct page *)); area->nr_pages = nr_pages; + pages = kmalloc_node(array_size, (gfp_mask & ~__GFP_HIGHMEM), node); /* Please note that the recursion is strictly bounded. */ - if (array_size > PAGE_SIZE) { + if (!pages && array_size > PAGE_SIZE) { pages = __vmalloc_node(array_size, gfp_mask, PAGE_KERNEL, node); area->flags |= VM_VPAGES; - } else - pages = kmalloc_node(array_size, (gfp_mask & ~__GFP_HIGHMEM), node); + } area->pages = pages; if (!area->pages) { remove_vm_area(area->addr); | |