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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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