On Thu, May 25, 2017 at 02:46:28PM +0800, Huang, Ying wrote:
> From: Huang Ying <ying.hu...@intel.com>
>
> In this patch, BIO_MAX_PAGES is changed from 256 to HPAGE_PMD_NR if
> CONFIG_THP_SWAP is enabled and HPAGE_PMD_NR > 256. This is to support
> THP (Transparent Huge Page) swap optimization. Where the THP will be
> write to disk as a whole instead of HPAGE_PMD_NR normal pages to batch
> the various operations during swap. And the page is likely to be
> written to disk to free memory when system memory goes really low, the
> memory pool need to be used to avoid deadlock.
>
> Signed-off-by: "Huang, Ying" <ying.hu...@intel.com>
> Cc: Johannes Weiner <han...@cmpxchg.org>
> Cc: Minchan Kim <minc...@kernel.org>
> Cc: Jens Axboe <ax...@kernel.dk>
> Cc: Ming Lei <tom.leim...@gmail.com>
> Cc: Shaohua Li <s...@fb.com>
> Cc: linux-bl...@vger.kernel.org
> ---
> include/linux/bio.h | 8 ++++++++
> 1 file changed, 8 insertions(+)
>
> diff --git a/include/linux/bio.h b/include/linux/bio.h
> index d1b04b0e99cf..314796486507 100644
> --- a/include/linux/bio.h
> +++ b/include/linux/bio.h
> @@ -38,7 +38,15 @@
> #define BIO_BUG_ON
> #endif
>
> +#ifdef CONFIG_THP_SWAP
> +#if HPAGE_PMD_NR > 256
> +#define BIO_MAX_PAGES HPAGE_PMD_NR
> +#else
> #define BIO_MAX_PAGES 256
> +#endif
> +#else
> +#define BIO_MAX_PAGES 256
> +#endif
>
> #define bio_prio(bio) (bio)->bi_ioprio
> #define bio_set_prio(bio, prio) ((bio)->bi_ioprio = prio)
Last time we discussed we should use multipage bvec for this usage.
I will rebase the last post on v4.12-rc and kick if off again since
the raid cleanup is just done on v4.11.
http://marc.info/?t=148453679000002&r=1&w=2
Thanks,
Ming
