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SubjectRe: [PATCH v7]: Hibernation: lower/better control the amount of pages used for buffering
Date
On Wednesday, March 28, 2012, Bojan Smojver wrote:
> Hi Rafael,
>
> And finally with an inline function.

OK, I'll take this one for v3.5. Thanks a lot for being persistent!

Rafael


> ---------------------------------------
> Hibernation/thaw improvements:
>
> 1. Set maximum number of pages for read buffering consistently, instead
> of inadvertently depending on the size of the sector type.
>
> 2. Use at most one quarter of free pages for read buffering.
>
> 3. Require that number of free pages when writing the image never falls
> below three quarters of total free pages available.
>
> Signed-off-by: Bojan Smojver <bojan@rexursive.com>
> ---
> kernel/power/swap.c | 35 ++++++++++++++++++++++++-----------
> 1 files changed, 24 insertions(+), 11 deletions(-)
>
> diff --git a/kernel/power/swap.c b/kernel/power/swap.c
> index 8742fd0..0e94fc6 100644
> --- a/kernel/power/swap.c
> +++ b/kernel/power/swap.c
> @@ -6,7 +6,7 @@
> *
> * Copyright (C) 1998,2001-2005 Pavel Machek <pavel@ucw.cz>
> * Copyright (C) 2006 Rafael J. Wysocki <rjw@sisk.pl>
> - * Copyright (C) 2010 Bojan Smojver <bojan@rexursive.com>
> + * Copyright (C) 2010-2012 Bojan Smojver <bojan@rexursive.com>
> *
> * This file is released under the GPLv2.
> *
> @@ -51,6 +51,15 @@
>
> #define MAP_PAGE_ENTRIES (PAGE_SIZE / sizeof(sector_t) - 1)
>
> +/*
> + * Number of pages required to be kept free while writing the image. Always
> + * three quarters of all available pages before the writing starts.
> + */
> +static inline unsigned long reqd_free_pages(void)
> +{
> + return (nr_free_pages() / 4) * 3;
> +}
> +
> struct swap_map_page {
> sector_t entries[MAP_PAGE_ENTRIES];
> sector_t next_swap;
> @@ -72,7 +81,7 @@ struct swap_map_handle {
> sector_t cur_swap;
> sector_t first_sector;
> unsigned int k;
> - unsigned long nr_free_pages, written;
> + unsigned long reqd_free_pages;
> u32 crc32;
> };
>
> @@ -316,8 +325,7 @@ static int get_swap_writer(struct swap_map_handle *handle)
> goto err_rel;
> }
> handle->k = 0;
> - handle->nr_free_pages = nr_free_pages() >> 1;
> - handle->written = 0;
> + handle->reqd_free_pages = reqd_free_pages();
> handle->first_sector = handle->cur_swap;
> return 0;
> err_rel:
> @@ -352,11 +360,15 @@ static int swap_write_page(struct swap_map_handle *handle, void *buf,
> handle->cur_swap = offset;
> handle->k = 0;
> }
> - if (bio_chain && ++handle->written > handle->nr_free_pages) {
> + if (bio_chain && nr_free_pages() < handle->reqd_free_pages) {
> error = hib_wait_on_bio_chain(bio_chain);
> if (error)
> goto out;
> - handle->written = 0;
> + /*
> + * Recalculate the number of required free pages, to make sure
> + * we never take more than a quarter.
> + */
> + handle->reqd_free_pages = reqd_free_pages();
> }
> out:
> return error;
> @@ -404,7 +416,7 @@ static int swap_writer_finish(struct swap_map_handle *handle,
> #define LZO_THREADS 3
>
> /* Maximum number of pages for read buffering. */
> -#define LZO_READ_PAGES (MAP_PAGE_ENTRIES * 8)
> +#define LZO_READ_PAGES 8192
>
>
> /**
> @@ -615,10 +627,10 @@ static int save_image_lzo(struct swap_map_handle *handle,
> }
>
> /*
> - * Adjust number of free pages after all allocations have been done.
> - * We don't want to run out of pages when writing.
> + * Adjust the number of required free pages after all allocations have
> + * been done. We don't want to run out of pages when writing.
> */
> - handle->nr_free_pages = nr_free_pages() >> 1;
> + handle->reqd_free_pages = reqd_free_pages();
>
> /*
> * Start the CRC32 thread.
> @@ -1129,8 +1141,9 @@ static int load_image_lzo(struct swap_map_handle *handle,
>
> /*
> * Adjust number of pages for read buffering, in case we are short.
> + * Never take more than a quarter of all available pages.
> */
> - read_pages = (nr_free_pages() - snapshot_get_image_size()) >> 1;
> + read_pages = (nr_free_pages() - snapshot_get_image_size()) / 4;
> read_pages = clamp_val(read_pages, LZO_CMP_PAGES, LZO_READ_PAGES);
>
> for (i = 0; i < read_pages; i++) {
> ---------------------------------------
>
>



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