On 07/03/2012 06:15 AM, Seth Jennings wrote:
> 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@xxxxxxxxxxxxxxxxxx>
> ---
> 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 a5ab720..9084565 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 10b0d60..a7a6f22 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)
firstpage is rather misleading.
As you know, we use firstpage term for real firstpage of zspage but
in case of zs_copy_map_object, it could be a middle page of zspage.
So I would like to use "page" instead of firstpage.
> +{
> + 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();
If I understand your intention correctly, you want to prevent calling
this function on non-atomic context. Right?
Please write down description more clearly as point of view what's happen
if we didn't.
> +
> + /* 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)
Ditto firstpage.
Otherwise, Looks good to me.
--
Kind regards,
Minchan Kim
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