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SubjectRe: [PATCH -mm] relayfs: support larger relay buffer
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On Tue, 2008-04-15 at 11:27 -0400, Masami Hiramatsu wrote:
> Use vmalloc() and memset() instead of kcalloc() to allocate a page* array
> when the array size is bigger than one page. This enables relayfs to support
> bigger relay buffers than 64MB on 4k-page system, 512MB on 16k-page system.
>
> Signed-off-by: Masami Hiramatsu <mhiramat@redhat.com>
> ---
> This is useful for a 64-bit system which has a plenty of memory (tens of
> giga bytes) and a large kernel memory space.
>
> I tested it on x86-64 and ia64.
>

Hi,

It looks ok to me, but it might be a little cleaner and avoid some
duplication if you add the new code as a couple of functions instead.
Just a suggestion...

Tom

> kernel/relay.c | 22 ++++++++++++++++++----
> 1 file changed, 18 insertions(+), 4 deletions(-)
>
> Index: 2.6.25-rc8-mm2/kernel/relay.c
> ===================================================================
> --- 2.6.25-rc8-mm2.orig/kernel/relay.c
> +++ 2.6.25-rc8-mm2/kernel/relay.c
> @@ -104,12 +104,20 @@ static int relay_mmap_buf(struct rchan_b
> static void *relay_alloc_buf(struct rchan_buf *buf, size_t *size)
> {
> void *mem;
> - unsigned int i, j, n_pages;
> + unsigned int i, j, n_pages, pa_size;
>
> *size = PAGE_ALIGN(*size);
> n_pages = *size >> PAGE_SHIFT;
> + pa_size = n_pages * sizeof(struct page *);
>
> - buf->page_array = kcalloc(n_pages, sizeof(struct page *), GFP_KERNEL);
> + if (pa_size > PAGE_SIZE) {
> + buf->page_array = vmalloc(pa_size);
> + if (buf->page_array)
> + memset(buf->page_array, 0, pa_size);
> + } else {
> + buf->page_array = kcalloc(n_pages, sizeof(struct page *),
> + GFP_KERNEL);
> + }
> if (!buf->page_array)
> return NULL;
>
> @@ -130,7 +138,10 @@ static void *relay_alloc_buf(struct rcha
> depopulate:
> for (j = 0; j < i; j++)
> __free_page(buf->page_array[j]);
> - kfree(buf->page_array);
> + if (pa_size > PAGE_SIZE)
> + vfree(buf->page_array);
> + else
> + kfree(buf->page_array);
> return NULL;
> }
>
> @@ -189,7 +200,10 @@ static void relay_destroy_buf(struct rch
> vunmap(buf->start);
> for (i = 0; i < buf->page_count; i++)
> __free_page(buf->page_array[i]);
> - kfree(buf->page_array);
> + if (buf->page_count * sizeof(struct page *) > PAGE_SIZE)
> + vfree(buf->page_array);
> + else
> + kfree(buf->page_array);
> }
> chan->buf[buf->cpu] = NULL;
> kfree(buf->padding);



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