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staging: zsmalloc: remove x86 dependency
This patch replaces the page table assisted object mapping method, which has x86 dependencies, with a arch-independent method that does a simple copy into a temporary per-cpu buffer. While a copy seems like it would be worse than mapping the pages, tests demonstrate the copying is always faster and, in the case of running inside a KVM guest, roughly 4x faster. Signed-off-by: Seth Jennings <sjenning@linux.vnet.ibm.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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@ -1,9 +1,5 @@
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config ZSMALLOC
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tristate "Memory allocator for compressed pages"
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# X86 dependency is because of the use of __flush_tlb_one and set_pte
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# in zsmalloc-main.c.
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# TODO: convert these to portable functions
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depends on X86
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default n
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help
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zsmalloc is a slab-based memory allocator designed to store
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@ -470,6 +470,57 @@ static struct page *find_get_zspage(struct size_class *class)
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return page;
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}
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static void zs_copy_map_object(char *buf, struct page *firstpage,
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int off, int size)
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{
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struct page *pages[2];
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int sizes[2];
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void *addr;
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pages[0] = firstpage;
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pages[1] = get_next_page(firstpage);
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BUG_ON(!pages[1]);
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sizes[0] = PAGE_SIZE - off;
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sizes[1] = size - sizes[0];
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/* disable page faults to match kmap_atomic() return conditions */
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pagefault_disable();
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/* copy object to per-cpu buffer */
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addr = kmap_atomic(pages[0]);
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memcpy(buf, addr + off, sizes[0]);
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kunmap_atomic(addr);
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addr = kmap_atomic(pages[1]);
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memcpy(buf + sizes[0], addr, sizes[1]);
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kunmap_atomic(addr);
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}
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static void zs_copy_unmap_object(char *buf, struct page *firstpage,
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int off, int size)
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{
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struct page *pages[2];
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int sizes[2];
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void *addr;
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pages[0] = firstpage;
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pages[1] = get_next_page(firstpage);
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BUG_ON(!pages[1]);
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sizes[0] = PAGE_SIZE - off;
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sizes[1] = size - sizes[0];
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/* copy per-cpu buffer to object */
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addr = kmap_atomic(pages[0]);
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memcpy(addr + off, buf, sizes[0]);
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kunmap_atomic(addr);
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addr = kmap_atomic(pages[1]);
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memcpy(addr, buf + sizes[0], sizes[1]);
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kunmap_atomic(addr);
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/* enable page faults to match kunmap_atomic() return conditions */
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pagefault_enable();
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}
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static int zs_cpu_notifier(struct notifier_block *nb, unsigned long action,
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void *pcpu)
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@ -480,18 +531,23 @@ static int zs_cpu_notifier(struct notifier_block *nb, unsigned long action,
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switch (action) {
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case CPU_UP_PREPARE:
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area = &per_cpu(zs_map_area, cpu);
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if (area->vm)
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break;
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area->vm = alloc_vm_area(2 * PAGE_SIZE, area->vm_ptes);
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if (!area->vm)
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return notifier_from_errno(-ENOMEM);
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/*
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* Make sure we don't leak memory if a cpu UP notification
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* and zs_init() race and both call zs_cpu_up() on the same cpu
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*/
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if (area->vm_buf)
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return 0;
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area->vm_buf = (char *)__get_free_page(GFP_KERNEL);
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if (!area->vm_buf)
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return -ENOMEM;
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return 0;
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break;
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case CPU_DEAD:
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case CPU_UP_CANCELED:
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area = &per_cpu(zs_map_area, cpu);
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if (area->vm)
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free_vm_area(area->vm);
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area->vm = NULL;
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if (area->vm_buf)
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free_page((unsigned long)area->vm_buf);
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area->vm_buf = NULL;
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break;
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}
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@ -714,22 +770,11 @@ void *zs_map_object(struct zs_pool *pool, unsigned long handle)
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if (off + class->size <= PAGE_SIZE) {
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/* this object is contained entirely within a page */
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area->vm_addr = kmap_atomic(page);
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} else {
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/* this object spans two pages */
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struct page *nextp;
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nextp = get_next_page(page);
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BUG_ON(!nextp);
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set_pte(area->vm_ptes[0], mk_pte(page, PAGE_KERNEL));
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set_pte(area->vm_ptes[1], mk_pte(nextp, PAGE_KERNEL));
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/* We pre-allocated VM area so mapping can never fail */
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area->vm_addr = area->vm->addr;
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return area->vm_addr + off;
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}
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return area->vm_addr + off;
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zs_copy_map_object(area->vm_buf, page, off, class->size);
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return area->vm_buf;
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}
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EXPORT_SYMBOL_GPL(zs_map_object);
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@ -751,14 +796,10 @@ void zs_unmap_object(struct zs_pool *pool, unsigned long handle)
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off = obj_idx_to_offset(page, obj_idx, class->size);
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area = &__get_cpu_var(zs_map_area);
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if (off + class->size <= PAGE_SIZE) {
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if (off + class->size <= PAGE_SIZE)
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kunmap_atomic(area->vm_addr);
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} else {
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set_pte(area->vm_ptes[0], __pte(0));
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set_pte(area->vm_ptes[1], __pte(0));
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__flush_tlb_one((unsigned long)area->vm_addr);
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__flush_tlb_one((unsigned long)area->vm_addr + PAGE_SIZE);
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}
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else
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zs_copy_unmap_object(area->vm_buf, page, off, class->size);
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put_cpu_var(zs_map_area);
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}
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EXPORT_SYMBOL_GPL(zs_unmap_object);
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@ -110,9 +110,8 @@ enum fullness_group {
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static const int fullness_threshold_frac = 4;
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struct mapping_area {
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struct vm_struct *vm;
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pte_t *vm_ptes[2];
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char *vm_addr;
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char *vm_buf; /* copy buffer for objects that span pages */
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char *vm_addr; /* address of kmap_atomic()'ed pages */
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};
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struct size_class {
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