From 5f601902c61e6cda627ec71c10609021067ed0fa Mon Sep 17 00:00:00 2001 From: Seth Jennings Date: Mon, 2 Jul 2012 16:15:49 -0500 Subject: [PATCH] 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 Signed-off-by: Greg Kroah-Hartman --- drivers/staging/zsmalloc/Kconfig | 4 - drivers/staging/zsmalloc/zsmalloc-main.c | 99 +++++++++++++++++------- drivers/staging/zsmalloc/zsmalloc_int.h | 5 +- 3 files changed, 72 insertions(+), 36 deletions(-) diff --git a/drivers/staging/zsmalloc/Kconfig b/drivers/staging/zsmalloc/Kconfig index a5ab7200626f..908456565796 100644 --- a/drivers/staging/zsmalloc/Kconfig +++ b/drivers/staging/zsmalloc/Kconfig @@ -1,9 +1,5 @@ config ZSMALLOC tristate "Memory allocator for compressed pages" - # X86 dependency is because of the use of __flush_tlb_one and set_pte - # in zsmalloc-main.c. - # TODO: convert these to portable functions - depends on X86 default n help zsmalloc is a slab-based memory allocator designed to store diff --git a/drivers/staging/zsmalloc/zsmalloc-main.c b/drivers/staging/zsmalloc/zsmalloc-main.c index 10b0d6000260..a7a6f225bbff 100644 --- a/drivers/staging/zsmalloc/zsmalloc-main.c +++ b/drivers/staging/zsmalloc/zsmalloc-main.c @@ -470,6 +470,57 @@ static struct page *find_get_zspage(struct size_class *class) return page; } +static void zs_copy_map_object(char *buf, struct page *firstpage, + int off, int size) +{ + struct page *pages[2]; + int sizes[2]; + void *addr; + + pages[0] = firstpage; + pages[1] = get_next_page(firstpage); + BUG_ON(!pages[1]); + + sizes[0] = PAGE_SIZE - off; + sizes[1] = size - sizes[0]; + + /* disable page faults to match kmap_atomic() return conditions */ + pagefault_disable(); + + /* copy object to per-cpu buffer */ + addr = kmap_atomic(pages[0]); + memcpy(buf, addr + off, sizes[0]); + kunmap_atomic(addr); + addr = kmap_atomic(pages[1]); + memcpy(buf + sizes[0], addr, sizes[1]); + kunmap_atomic(addr); +} + +static void zs_copy_unmap_object(char *buf, struct page *firstpage, + int off, int size) +{ + struct page *pages[2]; + int sizes[2]; + void *addr; + + pages[0] = firstpage; + pages[1] = get_next_page(firstpage); + BUG_ON(!pages[1]); + + sizes[0] = PAGE_SIZE - off; + sizes[1] = size - sizes[0]; + + /* copy per-cpu buffer to object */ + addr = kmap_atomic(pages[0]); + memcpy(addr + off, buf, sizes[0]); + kunmap_atomic(addr); + addr = kmap_atomic(pages[1]); + memcpy(addr, buf + sizes[0], sizes[1]); + kunmap_atomic(addr); + + /* enable page faults to match kunmap_atomic() return conditions */ + pagefault_enable(); +} static int zs_cpu_notifier(struct notifier_block *nb, unsigned long action, void *pcpu) @@ -480,18 +531,23 @@ static int zs_cpu_notifier(struct notifier_block *nb, unsigned long action, switch (action) { case CPU_UP_PREPARE: area = &per_cpu(zs_map_area, cpu); - if (area->vm) - break; - area->vm = alloc_vm_area(2 * PAGE_SIZE, area->vm_ptes); - if (!area->vm) - return notifier_from_errno(-ENOMEM); + /* + * Make sure we don't leak memory if a cpu UP notification + * and zs_init() race and both call zs_cpu_up() on the same cpu + */ + if (area->vm_buf) + return 0; + area->vm_buf = (char *)__get_free_page(GFP_KERNEL); + if (!area->vm_buf) + return -ENOMEM; + return 0; break; case CPU_DEAD: case CPU_UP_CANCELED: area = &per_cpu(zs_map_area, cpu); - if (area->vm) - free_vm_area(area->vm); - area->vm = NULL; + if (area->vm_buf) + free_page((unsigned long)area->vm_buf); + area->vm_buf = NULL; break; } @@ -714,22 +770,11 @@ void *zs_map_object(struct zs_pool *pool, unsigned long handle) if (off + class->size <= PAGE_SIZE) { /* this object is contained entirely within a page */ area->vm_addr = kmap_atomic(page); - } else { - /* this object spans two pages */ - struct page *nextp; - - nextp = get_next_page(page); - BUG_ON(!nextp); - - - set_pte(area->vm_ptes[0], mk_pte(page, PAGE_KERNEL)); - set_pte(area->vm_ptes[1], mk_pte(nextp, PAGE_KERNEL)); - - /* We pre-allocated VM area so mapping can never fail */ - area->vm_addr = area->vm->addr; + return area->vm_addr + off; } - return area->vm_addr + off; + zs_copy_map_object(area->vm_buf, page, off, class->size); + return area->vm_buf; } EXPORT_SYMBOL_GPL(zs_map_object); @@ -751,14 +796,10 @@ void zs_unmap_object(struct zs_pool *pool, unsigned long handle) off = obj_idx_to_offset(page, obj_idx, class->size); area = &__get_cpu_var(zs_map_area); - if (off + class->size <= PAGE_SIZE) { + if (off + class->size <= PAGE_SIZE) kunmap_atomic(area->vm_addr); - } else { - set_pte(area->vm_ptes[0], __pte(0)); - set_pte(area->vm_ptes[1], __pte(0)); - __flush_tlb_one((unsigned long)area->vm_addr); - __flush_tlb_one((unsigned long)area->vm_addr + PAGE_SIZE); - } + else + zs_copy_unmap_object(area->vm_buf, page, off, class->size); put_cpu_var(zs_map_area); } EXPORT_SYMBOL_GPL(zs_unmap_object); diff --git a/drivers/staging/zsmalloc/zsmalloc_int.h b/drivers/staging/zsmalloc/zsmalloc_int.h index 6fd32a9e0315..f760dae54f28 100644 --- a/drivers/staging/zsmalloc/zsmalloc_int.h +++ b/drivers/staging/zsmalloc/zsmalloc_int.h @@ -110,9 +110,8 @@ enum fullness_group { static const int fullness_threshold_frac = 4; struct mapping_area { - struct vm_struct *vm; - pte_t *vm_ptes[2]; - char *vm_addr; + char *vm_buf; /* copy buffer for objects that span pages */ + char *vm_addr; /* address of kmap_atomic()'ed pages */ }; struct size_class { -- GitLab