On Sat, Sep 22, 2012 at 04:03:13PM +0530, raghu.prabhu13@xxxxxxxxx wrote:
> From: Raghavendra D Prabhu <rprabhu@xxxxxxxxxxx>
>
> page_cache_sync_readahead checks for ra->ra_pages again, so moving the check
> after VM_SequentialReadHint.
Well it depends on what case you are optimizing for. I suspect there
are much more tmpfs users than VM_SequentialReadHint users. So this
change is actually not desirable wrt the more widely used cases.
Thanks,
Fengguang
> Signed-off-by: Raghavendra D Prabhu <rprabhu@xxxxxxxxxxx>
> ---
> mm/filemap.c | 5 +++--
> 1 file changed, 3 insertions(+), 2 deletions(-)
>
> diff --git a/mm/filemap.c b/mm/filemap.c
> index 3843445..606a648 100644
> --- a/mm/filemap.c
> +++ b/mm/filemap.c
> @@ -1523,8 +1523,6 @@ static void do_sync_mmap_readahead(struct vm_area_struct *vma,
> /* If we don't want any read-ahead, don't bother */
> if (VM_RandomReadHint(vma))
> return;
> - if (!ra->ra_pages)
> - return;
>
> if (VM_SequentialReadHint(vma)) {
> page_cache_sync_readahead(mapping, ra, file, offset,
> @@ -1532,6 +1530,9 @@ static void do_sync_mmap_readahead(struct vm_area_struct *vma,
> return;
> }
>
> + if (!ra->ra_pages)
> + return;
> +
> /* Avoid banging the cache line if not needed */
> if (ra->mmap_miss < MMAP_LOTSAMISS * 10)
> ra->mmap_miss++;
> --
> 1.7.12.1
>
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