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Message-Id: <201204292307.52040.rjw@sisk.pl>
Date: Sun, 29 Apr 2012 23:07:51 +0200
From: "Rafael J. Wysocki" <rjw@...k.pl>
To: Bojan Smojver <bojan@...ursive.com>
Cc: Per Olofsson <pelle@...ian.org>, linux-kernel@...r.kernel.org,
Linux PM list <linux-pm@...r.kernel.org>
Subject: Re: [PATCH v11]: Hibernation: fix the number of pages used for hibernate/thaw buffering
On Friday, April 27, 2012, Bojan Smojver wrote:
> On Fri, 2012-04-27 at 00:11 +0200, Rafael J. Wysocki wrote:
> > Can you just create a second patch on top of what's in linux-next now?
>
> Here it is.
>
> ---------------------------------------
> Hibernation/thaw fixes/improvements:
>
> 1. Do not allocate memory for buffers from emergency pools, unless
> absolutely required. Do not warn about and do not retry non-essential
> failed allocations.
>
> 2. Do not check the amount of free pages left on every single page
> write, but wait until one map is completely populated and then check.
>
> 3. Set maximum number of pages for read buffering consistently, instead
> of inadvertently depending on the size of the sector type.
>
> 4. Fix copyright line, which I missed when I submitted the hibernation
> threading patch.
>
> 5. Dispense with bit shifting arithmetic to improve readability.
>
> 6. Really recalculate the number of pages required to be free after all
> allocations have been done.
>
> 7. Fix calculation of pages required for read buffering. Only count in
> pages that do not belong to high memory.
>
> Signed-off-by: Bojan Smojver <bojan@...ursive.com>
Applied to linux-pm/linux-next.
Thanks,
Rafael
> ---
> kernel/power/swap.c | 62 ++++++++++++++++++++++++++++++++-------------------
> 1 files changed, 39 insertions(+), 23 deletions(-)
>
> diff --git a/kernel/power/swap.c b/kernel/power/swap.c
> index eef311a..11e22c0 100644
> --- a/kernel/power/swap.c
> +++ b/kernel/power/swap.c
> @@ -6,7 +6,7 @@
> *
> * Copyright (C) 1998,2001-2005 Pavel Machek <pavel@....cz>
> * Copyright (C) 2006 Rafael J. Wysocki <rjw@...k.pl>
> - * Copyright (C) 2010 Bojan Smojver <bojan@...ursive.com>
> + * Copyright (C) 2010-2012 Bojan Smojver <bojan@...ursive.com>
> *
> * This file is released under the GPLv2.
> *
> @@ -282,14 +282,17 @@ static int write_page(void *buf, sector_t offset, struct bio **bio_chain)
> return -ENOSPC;
>
> if (bio_chain) {
> - src = (void *)__get_free_page(__GFP_WAIT | __GFP_HIGH);
> + src = (void *)__get_free_page(__GFP_WAIT | __GFP_NOWARN |
> + __GFP_NORETRY);
> if (src) {
> copy_page(src, buf);
> } else {
> ret = hib_wait_on_bio_chain(bio_chain); /* Free pages */
> if (ret)
> return ret;
> - src = (void *)__get_free_page(__GFP_WAIT | __GFP_HIGH);
> + src = (void *)__get_free_page(__GFP_WAIT |
> + __GFP_NOWARN |
> + __GFP_NORETRY);
> if (src) {
> copy_page(src, buf);
> } else {
> @@ -367,12 +370,17 @@ static int swap_write_page(struct swap_map_handle *handle, void *buf,
> clear_page(handle->cur);
> handle->cur_swap = offset;
> handle->k = 0;
> - }
> - if (bio_chain && low_free_pages() <= handle->reqd_free_pages) {
> - error = hib_wait_on_bio_chain(bio_chain);
> - if (error)
> - goto out;
> - handle->reqd_free_pages = reqd_free_pages();
> +
> + if (bio_chain && low_free_pages() <= handle->reqd_free_pages) {
> + error = hib_wait_on_bio_chain(bio_chain);
> + if (error)
> + goto out;
> + /*
> + * Recalculate the number of required free pages, to
> + * make sure we never take more than half.
> + */
> + handle->reqd_free_pages = reqd_free_pages();
> + }
> }
> out:
> return error;
> @@ -419,8 +427,9 @@ static int swap_writer_finish(struct swap_map_handle *handle,
> /* Maximum number of threads for compression/decompression. */
> #define LZO_THREADS 3
>
> -/* Maximum number of pages for read buffering. */
> -#define LZO_READ_PAGES (MAP_PAGE_ENTRIES * 8)
> +/* Minimum/maximum number of pages for read buffering. */
> +#define LZO_MIN_RD_PAGES 1024
> +#define LZO_MAX_RD_PAGES 8192
>
>
> /**
> @@ -631,12 +640,6 @@ 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.
> - */
> - handle->reqd_free_pages = reqd_free_pages();
> -
> - /*
> * Start the CRC32 thread.
> */
> init_waitqueue_head(&crc->go);
> @@ -657,6 +660,12 @@ static int save_image_lzo(struct swap_map_handle *handle,
> goto out_clean;
> }
>
> + /*
> + * 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->reqd_free_pages = reqd_free_pages();
> +
> printk(KERN_INFO
> "PM: Using %u thread(s) for compression.\n"
> "PM: Compressing and saving image data (%u pages) ... ",
> @@ -1067,7 +1076,7 @@ static int load_image_lzo(struct swap_map_handle *handle,
> unsigned i, thr, run_threads, nr_threads;
> unsigned ring = 0, pg = 0, ring_size = 0,
> have = 0, want, need, asked = 0;
> - unsigned long read_pages;
> + unsigned long read_pages = 0;
> unsigned char **page = NULL;
> struct dec_data *data = NULL;
> struct crc_data *crc = NULL;
> @@ -1079,7 +1088,7 @@ static int load_image_lzo(struct swap_map_handle *handle,
> nr_threads = num_online_cpus() - 1;
> nr_threads = clamp_val(nr_threads, 1, LZO_THREADS);
>
> - page = vmalloc(sizeof(*page) * LZO_READ_PAGES);
> + page = vmalloc(sizeof(*page) * LZO_MAX_RD_PAGES);
> if (!page) {
> printk(KERN_ERR "PM: Failed to allocate LZO page\n");
> ret = -ENOMEM;
> @@ -1144,15 +1153,22 @@ static int load_image_lzo(struct swap_map_handle *handle,
> }
>
> /*
> - * Adjust number of pages for read buffering, in case we are short.
> + * Set the number of pages for read buffering.
> + * This is complete guesswork, because we'll only know the real
> + * picture once prepare_image() is called, which is much later on
> + * during the image load phase. We'll assume the worst case and
> + * say that none of the image pages are from high memory.
> */
> - read_pages = (nr_free_pages() - snapshot_get_image_size()) >> 1;
> - read_pages = clamp_val(read_pages, LZO_CMP_PAGES, LZO_READ_PAGES);
> + if (low_free_pages() > snapshot_get_image_size())
> + read_pages = (low_free_pages() - snapshot_get_image_size()) / 2;
> + read_pages = clamp_val(read_pages, LZO_MIN_RD_PAGES, LZO_MAX_RD_PAGES);
>
> for (i = 0; i < read_pages; i++) {
> page[i] = (void *)__get_free_page(i < LZO_CMP_PAGES ?
> __GFP_WAIT | __GFP_HIGH :
> - __GFP_WAIT);
> + __GFP_WAIT | __GFP_NOWARN |
> + __GFP_NORETRY);
> +
> if (!page[i]) {
> if (i < LZO_CMP_PAGES) {
> ring_size = i;
> ---------------------------------------
>
>
--
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