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Message-Id: <201110140008.52643.rjw@sisk.pl>
Date:	Fri, 14 Oct 2011 00:08:52 +0200
From:	"Rafael J. Wysocki" <rjw@...k.pl>
To:	Bojan Smojver <bojan@...ursive.com>
Cc:	linux-kernel@...r.kernel.org,
	Linux PM list <linux-pm@...r.kernel.org>
Subject: Re: [PATCH v11]: Improve performance of LZO/plain hibernation, check image with CRC32

On Tuesday, October 11, 2011, Bojan Smojver wrote:
> OK, one more. Sorry :-(
> 
> Just a bit of paranoia regarding the new variable read_pages - we don't
> want to cut higher bits off it accidentally. Oh, and as it turns out,
> the kernel has a nice little macro called clamp_val. :-) 
> 
> ---------------------------------------
> Use threads for LZO compression/decompression on hibernate/thaw.
> Improve buffering on hibernate/thaw.
> Calculate/verify CRC32 of the image pages on hibernate/thaw.
> v11
> 
> In my testing, this improved write/read speed by a factor of about two.

Applied to linux-pm/linux-next.

Thanks,
Rafael


> Signed-off-by: Bojan Smojver <bojan@...ursive.com>
> ---
>  kernel/power/Kconfig     |    1 +
>  kernel/power/hibernate.c |    3 +
>  kernel/power/power.h     |    1 +
>  kernel/power/swap.c      |  818 ++++++++++++++++++++++++++++++++++++----------
>  4 files changed, 645 insertions(+), 178 deletions(-)
> 
> diff --git a/kernel/power/Kconfig b/kernel/power/Kconfig
> index 3744c59..e675045 100644
> --- a/kernel/power/Kconfig
> +++ b/kernel/power/Kconfig
> @@ -27,6 +27,7 @@ config HIBERNATION
>  	select HIBERNATE_CALLBACKS
>  	select LZO_COMPRESS
>  	select LZO_DECOMPRESS
> +	select CRC32
>  	---help---
>  	  Enable the suspend to disk (STD) functionality, which is usually
>  	  called "hibernation" in user interfaces.  STD checkpoints the
> diff --git a/kernel/power/hibernate.c b/kernel/power/hibernate.c
> index 8f7b1db..5c8aa9c 100644
> --- a/kernel/power/hibernate.c
> +++ b/kernel/power/hibernate.c
> @@ -650,6 +650,9 @@ int hibernate(void)
>  			flags |= SF_PLATFORM_MODE;
>  		if (nocompress)
>  			flags |= SF_NOCOMPRESS_MODE;
> +		else
> +		        flags |= SF_CRC32_MODE;
> +
>  		pr_debug("PM: writing image.\n");
>  		error = swsusp_write(flags);
>  		swsusp_free();
> diff --git a/kernel/power/power.h b/kernel/power/power.h
> index 9a00a0a..f543583 100644
> --- a/kernel/power/power.h
> +++ b/kernel/power/power.h
> @@ -146,6 +146,7 @@ extern int swsusp_swap_in_use(void);
>   */
>  #define SF_PLATFORM_MODE	1
>  #define SF_NOCOMPRESS_MODE	2
> +#define SF_CRC32_MODE	        4
>  
>  /* kernel/power/hibernate.c */
>  extern int swsusp_check(void);
> diff --git a/kernel/power/swap.c b/kernel/power/swap.c
> index 7c97c3a..11a594c 100644
> --- a/kernel/power/swap.c
> +++ b/kernel/power/swap.c
> @@ -27,6 +27,10 @@
>  #include <linux/slab.h>
>  #include <linux/lzo.h>
>  #include <linux/vmalloc.h>
> +#include <linux/cpumask.h>
> +#include <linux/atomic.h>
> +#include <linux/kthread.h>
> +#include <linux/crc32.h>
>  
>  #include "power.h"
>  
> @@ -43,8 +47,7 @@
>   *	allocated and populated one at a time, so we only need one memory
>   *	page to set up the entire structure.
>   *
> - *	During resume we also only need to use one swap_map_page structure
> - *	at a time.
> + *	During resume we pick up all swap_map_page structures into a list.
>   */
>  
>  #define MAP_PAGE_ENTRIES	(PAGE_SIZE / sizeof(sector_t) - 1)
> @@ -54,6 +57,11 @@ struct swap_map_page {
>  	sector_t next_swap;
>  };
>  
> +struct swap_map_page_list {
> +	struct swap_map_page *map;
> +	struct swap_map_page_list *next;
> +};
> +
>  /**
>   *	The swap_map_handle structure is used for handling swap in
>   *	a file-alike way
> @@ -61,13 +69,18 @@ struct swap_map_page {
>  
>  struct swap_map_handle {
>  	struct swap_map_page *cur;
> +	struct swap_map_page_list *maps;
>  	sector_t cur_swap;
>  	sector_t first_sector;
>  	unsigned int k;
> +	unsigned long nr_free_pages, written;
> +	u32 crc32;
>  };
>  
>  struct swsusp_header {
> -	char reserved[PAGE_SIZE - 20 - sizeof(sector_t) - sizeof(int)];
> +	char reserved[PAGE_SIZE - 20 - sizeof(sector_t) - sizeof(int) -
> +	              sizeof(u32)];
> +	u32	crc32;
>  	sector_t image;
>  	unsigned int flags;	/* Flags to pass to the "boot" kernel */
>  	char	orig_sig[10];
> @@ -199,6 +212,8 @@ static int mark_swapfiles(struct swap_map_handle *handle, unsigned int flags)
>  		memcpy(swsusp_header->sig, HIBERNATE_SIG, 10);
>  		swsusp_header->image = handle->first_sector;
>  		swsusp_header->flags = flags;
> +		if (flags & SF_CRC32_MODE)
> +			swsusp_header->crc32 = handle->crc32;
>  		error = hib_bio_write_page(swsusp_resume_block,
>  					swsusp_header, NULL);
>  	} else {
> @@ -245,6 +260,7 @@ static int swsusp_swap_check(void)
>  static int write_page(void *buf, sector_t offset, struct bio **bio_chain)
>  {
>  	void *src;
> +	int ret;
>  
>  	if (!offset)
>  		return -ENOSPC;
> @@ -254,9 +270,17 @@ static int write_page(void *buf, sector_t offset, struct bio **bio_chain)
>  		if (src) {
>  			copy_page(src, buf);
>  		} else {
> -			WARN_ON_ONCE(1);
> -			bio_chain = NULL;	/* Go synchronous */
> -			src = buf;
> +			ret = hib_wait_on_bio_chain(bio_chain); /* Free pages */
> +			if (ret)
> +				return ret;
> +			src = (void *)__get_free_page(__GFP_WAIT | __GFP_HIGH);
> +			if (src) {
> +				copy_page(src, buf);
> +			} else {
> +				WARN_ON_ONCE(1);
> +				bio_chain = NULL;	/* Go synchronous */
> +				src = buf;
> +			}
>  		}
>  	} else {
>  		src = buf;
> @@ -293,6 +317,8 @@ 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->first_sector = handle->cur_swap;
>  	return 0;
>  err_rel:
> @@ -316,20 +342,23 @@ static int swap_write_page(struct swap_map_handle *handle, void *buf,
>  		return error;
>  	handle->cur->entries[handle->k++] = offset;
>  	if (handle->k >= MAP_PAGE_ENTRIES) {
> -		error = hib_wait_on_bio_chain(bio_chain);
> -		if (error)
> -			goto out;
>  		offset = alloc_swapdev_block(root_swap);
>  		if (!offset)
>  			return -ENOSPC;
>  		handle->cur->next_swap = offset;
> -		error = write_page(handle->cur, handle->cur_swap, NULL);
> +		error = write_page(handle->cur, handle->cur_swap, bio_chain);
>  		if (error)
>  			goto out;
>  		clear_page(handle->cur);
>  		handle->cur_swap = offset;
>  		handle->k = 0;
>  	}
> +	if (bio_chain && ++handle->written > handle->nr_free_pages) {
> +		error = hib_wait_on_bio_chain(bio_chain);
> +		if (error)
> +			goto out;
> +		handle->written = 0;
> +	}
>   out:
>  	return error;
>  }
> @@ -372,6 +401,13 @@ static int swap_writer_finish(struct swap_map_handle *handle,
>  			             LZO_HEADER, PAGE_SIZE)
>  #define LZO_CMP_SIZE	(LZO_CMP_PAGES * PAGE_SIZE)
>  
> +/* 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)
> +
> +
>  /**
>   *	save_image - save the suspend image data
>   */
> @@ -419,6 +455,92 @@ static int save_image(struct swap_map_handle *handle,
>  	return ret;
>  }
>  
> +/**
> + * Structure used for CRC32.
> + */
> +struct crc_data {
> +	struct task_struct *thr;                  /* thread */
> +	atomic_t ready;                           /* ready to start flag */
> +	atomic_t stop;                            /* ready to stop flag */
> +	unsigned run_threads;                     /* nr current threads */
> +	wait_queue_head_t go;                     /* start crc update */
> +	wait_queue_head_t done;                   /* crc update done */
> +	u32 *crc32;                               /* points to handle's crc32 */
> +	size_t *unc_len[LZO_THREADS];             /* uncompressed lengths */
> +	unsigned char *unc[LZO_THREADS];          /* uncompressed data */
> +};
> +
> +/**
> + * CRC32 update function that runs in its own thread.
> + */
> +static int crc32_threadfn(void *data)
> +{
> +	struct crc_data *d = data;
> +	unsigned i;
> +
> +	while (1) {
> +		wait_event(d->go, atomic_read(&d->ready) ||
> +		                  kthread_should_stop());
> +		if (kthread_should_stop()) {
> +			d->thr = NULL;
> +			atomic_set(&d->stop, 1);
> +			wake_up(&d->done);
> +			break;
> +		}
> +		atomic_set(&d->ready, 0);
> +
> +		for (i = 0; i < d->run_threads; i++)
> +			*d->crc32 = crc32_le(*d->crc32,
> +			                     d->unc[i], *d->unc_len[i]);
> +		atomic_set(&d->stop, 1);
> +		wake_up(&d->done);
> +	}
> +	return 0;
> +}
> +/**
> + * Structure used for LZO data compression.
> + */
> +struct cmp_data {
> +	struct task_struct *thr;                  /* thread */
> +	atomic_t ready;                           /* ready to start flag */
> +	atomic_t stop;                            /* ready to stop flag */
> +	int ret;                                  /* return code */
> +	wait_queue_head_t go;                     /* start compression */
> +	wait_queue_head_t done;                   /* compression done */
> +	size_t unc_len;                           /* uncompressed length */
> +	size_t cmp_len;                           /* compressed length */
> +	unsigned char unc[LZO_UNC_SIZE];          /* uncompressed buffer */
> +	unsigned char cmp[LZO_CMP_SIZE];          /* compressed buffer */
> +	unsigned char wrk[LZO1X_1_MEM_COMPRESS];  /* compression workspace */
> +};
> +
> +/**
> + * Compression function that runs in its own thread.
> + */
> +static int lzo_compress_threadfn(void *data)
> +{
> +	struct cmp_data *d = data;
> +
> +	while (1) {
> +		wait_event(d->go, atomic_read(&d->ready) ||
> +		                  kthread_should_stop());
> +		if (kthread_should_stop()) {
> +			d->thr = NULL;
> +			d->ret = -1;
> +			atomic_set(&d->stop, 1);
> +			wake_up(&d->done);
> +			break;
> +		}
> +		atomic_set(&d->ready, 0);
> +
> +		d->ret = lzo1x_1_compress(d->unc, d->unc_len,
> +		                          d->cmp + LZO_HEADER, &d->cmp_len,
> +		                          d->wrk);
> +		atomic_set(&d->stop, 1);
> +		wake_up(&d->done);
> +	}
> +	return 0;
> +}
>  
>  /**
>   * save_image_lzo - Save the suspend image data compressed with LZO.
> @@ -437,42 +559,93 @@ static int save_image_lzo(struct swap_map_handle *handle,
>  	struct bio *bio;
>  	struct timeval start;
>  	struct timeval stop;
> -	size_t off, unc_len, cmp_len;
> -	unsigned char *unc, *cmp, *wrk, *page;
> +	size_t off;
> +	unsigned thr, run_threads, nr_threads;
> +	unsigned char *page = NULL;
> +	struct cmp_data *data = NULL;
> +	struct crc_data *crc = NULL;
> +
> +	/*
> +	 * We'll limit the number of threads for compression to limit memory
> +	 * footprint.
> +	 */
> +	nr_threads = num_online_cpus() - 1;
> +	nr_threads = clamp_val(nr_threads, 1, LZO_THREADS);
>  
>  	page = (void *)__get_free_page(__GFP_WAIT | __GFP_HIGH);
>  	if (!page) {
>  		printk(KERN_ERR "PM: Failed to allocate LZO page\n");
> -		return -ENOMEM;
> +		ret = -ENOMEM;
> +		goto out_clean;
>  	}
>  
> -	wrk = vmalloc(LZO1X_1_MEM_COMPRESS);
> -	if (!wrk) {
> -		printk(KERN_ERR "PM: Failed to allocate LZO workspace\n");
> -		free_page((unsigned long)page);
> -		return -ENOMEM;
> +	data = vmalloc(sizeof(*data) * nr_threads);
> +	if (!data) {
> +		printk(KERN_ERR "PM: Failed to allocate LZO data\n");
> +		ret = -ENOMEM;
> +		goto out_clean;
>  	}
> +	for (thr = 0; thr < nr_threads; thr++)
> +		memset(&data[thr], 0, offsetof(struct cmp_data, go));
>  
> -	unc = vmalloc(LZO_UNC_SIZE);
> -	if (!unc) {
> -		printk(KERN_ERR "PM: Failed to allocate LZO uncompressed\n");
> -		vfree(wrk);
> -		free_page((unsigned long)page);
> -		return -ENOMEM;
> +	crc = kmalloc(sizeof(*crc), GFP_KERNEL);
> +	if (!crc) {
> +		printk(KERN_ERR "PM: Failed to allocate crc\n");
> +		ret = -ENOMEM;
> +		goto out_clean;
> +	}
> +	memset(crc, 0, offsetof(struct crc_data, go));
> +
> +	/*
> +	 * Start the compression threads.
> +	 */
> +	for (thr = 0; thr < nr_threads; thr++) {
> +		init_waitqueue_head(&data[thr].go);
> +		init_waitqueue_head(&data[thr].done);
> +
> +		data[thr].thr = kthread_run(lzo_compress_threadfn,
> +		                            &data[thr],
> +		                            "image_compress/%u", thr);
> +		if (IS_ERR(data[thr].thr)) {
> +			data[thr].thr = NULL;
> +			printk(KERN_ERR
> +			       "PM: Cannot start compression threads\n");
> +			ret = -ENOMEM;
> +			goto out_clean;
> +		}
>  	}
>  
> -	cmp = vmalloc(LZO_CMP_SIZE);
> -	if (!cmp) {
> -		printk(KERN_ERR "PM: Failed to allocate LZO compressed\n");
> -		vfree(unc);
> -		vfree(wrk);
> -		free_page((unsigned long)page);
> -		return -ENOMEM;
> +	/*
> +	 * Adjust number of 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;
> +
> +	/*
> +	 * Start the CRC32 thread.
> +	 */
> +	init_waitqueue_head(&crc->go);
> +	init_waitqueue_head(&crc->done);
> +
> +	handle->crc32 = 0;
> +	crc->crc32 = &handle->crc32;
> +	for (thr = 0; thr < nr_threads; thr++) {
> +		crc->unc[thr] = data[thr].unc;
> +		crc->unc_len[thr] = &data[thr].unc_len;
> +	}
> +
> +	crc->thr = kthread_run(crc32_threadfn, crc, "image_crc32");
> +	if (IS_ERR(crc->thr)) {
> +		crc->thr = NULL;
> +		printk(KERN_ERR "PM: Cannot start CRC32 thread\n");
> +		ret = -ENOMEM;
> +		goto out_clean;
>  	}
>  
>  	printk(KERN_INFO
> +		"PM: Using %u thread(s) for compression.\n"
>  		"PM: Compressing and saving image data (%u pages) ...     ",
> -		nr_to_write);
> +		nr_threads, nr_to_write);
>  	m = nr_to_write / 100;
>  	if (!m)
>  		m = 1;
> @@ -480,55 +653,83 @@ static int save_image_lzo(struct swap_map_handle *handle,
>  	bio = NULL;
>  	do_gettimeofday(&start);
>  	for (;;) {
> -		for (off = 0; off < LZO_UNC_SIZE; off += PAGE_SIZE) {
> -			ret = snapshot_read_next(snapshot);
> -			if (ret < 0)
> -				goto out_finish;
> -
> -			if (!ret)
> +		for (thr = 0; thr < nr_threads; thr++) {
> +			for (off = 0; off < LZO_UNC_SIZE; off += PAGE_SIZE) {
> +				ret = snapshot_read_next(snapshot);
> +				if (ret < 0)
> +					goto out_finish;
> +
> +				if (!ret)
> +					break;
> +
> +				memcpy(data[thr].unc + off,
> +				       data_of(*snapshot), PAGE_SIZE);
> +
> +				if (!(nr_pages % m))
> +					printk(KERN_CONT "\b\b\b\b%3d%%",
> +				               nr_pages / m);
> +				nr_pages++;
> +			}
> +			if (!off)
>  				break;
>  
> -			memcpy(unc + off, data_of(*snapshot), PAGE_SIZE);
> +			data[thr].unc_len = off;
>  
> -			if (!(nr_pages % m))
> -				printk(KERN_CONT "\b\b\b\b%3d%%", nr_pages / m);
> -			nr_pages++;
> +			atomic_set(&data[thr].ready, 1);
> +			wake_up(&data[thr].go);
>  		}
>  
> -		if (!off)
> +		if (!thr)
>  			break;
>  
> -		unc_len = off;
> -		ret = lzo1x_1_compress(unc, unc_len,
> -		                       cmp + LZO_HEADER, &cmp_len, wrk);
> -		if (ret < 0) {
> -			printk(KERN_ERR "PM: LZO compression failed\n");
> -			break;
> -		}
> +		crc->run_threads = thr;
> +		atomic_set(&crc->ready, 1);
> +		wake_up(&crc->go);
>  
> -		if (unlikely(!cmp_len ||
> -		             cmp_len > lzo1x_worst_compress(unc_len))) {
> -			printk(KERN_ERR "PM: Invalid LZO compressed length\n");
> -			ret = -1;
> -			break;
> -		}
> +		for (run_threads = thr, thr = 0; thr < run_threads; thr++) {
> +			wait_event(data[thr].done,
> +			           atomic_read(&data[thr].stop));
> +			atomic_set(&data[thr].stop, 0);
>  
> -		*(size_t *)cmp = cmp_len;
> +			ret = data[thr].ret;
>  
> -		/*
> -		 * Given we are writing one page at a time to disk, we copy
> -		 * that much from the buffer, although the last bit will likely
> -		 * be smaller than full page. This is OK - we saved the length
> -		 * of the compressed data, so any garbage at the end will be
> -		 * discarded when we read it.
> -		 */
> -		for (off = 0; off < LZO_HEADER + cmp_len; off += PAGE_SIZE) {
> -			memcpy(page, cmp + off, PAGE_SIZE);
> +			if (ret < 0) {
> +				printk(KERN_ERR "PM: LZO compression failed\n");
> +				goto out_finish;
> +			}
>  
> -			ret = swap_write_page(handle, page, &bio);
> -			if (ret)
> +			if (unlikely(!data[thr].cmp_len ||
> +			             data[thr].cmp_len >
> +			             lzo1x_worst_compress(data[thr].unc_len))) {
> +				printk(KERN_ERR
> +				       "PM: Invalid LZO compressed length\n");
> +				ret = -1;
>  				goto out_finish;
> +			}
> +
> +			*(size_t *)data[thr].cmp = data[thr].cmp_len;
> +
> +			/*
> +			 * Given we are writing one page at a time to disk, we
> +			 * copy that much from the buffer, although the last
> +			 * bit will likely be smaller than full page. This is
> +			 * OK - we saved the length of the compressed data, so
> +			 * any garbage at the end will be discarded when we
> +			 * read it.
> +			 */
> +			for (off = 0;
> +			     off < LZO_HEADER + data[thr].cmp_len;
> +			     off += PAGE_SIZE) {
> +				memcpy(page, data[thr].cmp + off, PAGE_SIZE);
> +
> +				ret = swap_write_page(handle, page, &bio);
> +				if (ret)
> +					goto out_finish;
> +			}
>  		}
> +
> +		wait_event(crc->done, atomic_read(&crc->stop));
> +		atomic_set(&crc->stop, 0);
>  	}
>  
>  out_finish:
> @@ -536,16 +737,25 @@ out_finish:
>  	do_gettimeofday(&stop);
>  	if (!ret)
>  		ret = err2;
> -	if (!ret)
> +	if (!ret) {
>  		printk(KERN_CONT "\b\b\b\bdone\n");
> -	else
> +	} else {
>  		printk(KERN_CONT "\n");
> +	}
>  	swsusp_show_speed(&start, &stop, nr_to_write, "Wrote");
> -
> -	vfree(cmp);
> -	vfree(unc);
> -	vfree(wrk);
> -	free_page((unsigned long)page);
> +out_clean:
> +	if (crc) {
> +		if (crc->thr)
> +			kthread_stop(crc->thr);
> +		kfree(crc);
> +	}
> +	if (data) {
> +		for (thr = 0; thr < nr_threads; thr++)
> +			if (data[thr].thr)
> +				kthread_stop(data[thr].thr);
> +		vfree(data);
> +	}
> +	if (page) free_page((unsigned long)page);
>  
>  	return ret;
>  }
> @@ -625,8 +835,15 @@ out_finish:
>  
>  static void release_swap_reader(struct swap_map_handle *handle)
>  {
> -	if (handle->cur)
> -		free_page((unsigned long)handle->cur);
> +	struct swap_map_page_list *tmp;
> +
> +	while (handle->maps) {
> +		if (handle->maps->map)
> +			free_page((unsigned long)handle->maps->map);
> +		tmp = handle->maps;
> +		handle->maps = handle->maps->next;
> +		kfree(tmp);
> +	}
>  	handle->cur = NULL;
>  }
>  
> @@ -634,22 +851,46 @@ static int get_swap_reader(struct swap_map_handle *handle,
>  		unsigned int *flags_p)
>  {
>  	int error;
> +	struct swap_map_page_list *tmp, *last;
> +	sector_t offset;
>  
>  	*flags_p = swsusp_header->flags;
>  
>  	if (!swsusp_header->image) /* how can this happen? */
>  		return -EINVAL;
>  
> -	handle->cur = (struct swap_map_page *)get_zeroed_page(__GFP_WAIT | __GFP_HIGH);
> -	if (!handle->cur)
> -		return -ENOMEM;
> +	handle->cur = NULL;
> +	last = handle->maps = NULL;
> +	offset = swsusp_header->image;
> +	while (offset) {
> +		tmp = kmalloc(sizeof(*handle->maps), GFP_KERNEL);
> +		if (!tmp) {
> +			release_swap_reader(handle);
> +			return -ENOMEM;
> +		}
> +		memset(tmp, 0, sizeof(*tmp));
> +		if (!handle->maps)
> +			handle->maps = tmp;
> +		if (last)
> +			last->next = tmp;
> +		last = tmp;
> +
> +		tmp->map = (struct swap_map_page *)
> +		           __get_free_page(__GFP_WAIT | __GFP_HIGH);
> +		if (!tmp->map) {
> +			release_swap_reader(handle);
> +			return -ENOMEM;
> +		}
>  
> -	error = hib_bio_read_page(swsusp_header->image, handle->cur, NULL);
> -	if (error) {
> -		release_swap_reader(handle);
> -		return error;
> +		error = hib_bio_read_page(offset, tmp->map, NULL);
> +		if (error) {
> +			release_swap_reader(handle);
> +			return error;
> +		}
> +		offset = tmp->map->next_swap;
>  	}
>  	handle->k = 0;
> +	handle->cur = handle->maps->map;
>  	return 0;
>  }
>  
> @@ -658,6 +899,7 @@ static int swap_read_page(struct swap_map_handle *handle, void *buf,
>  {
>  	sector_t offset;
>  	int error;
> +	struct swap_map_page_list *tmp;
>  
>  	if (!handle->cur)
>  		return -EINVAL;
> @@ -668,13 +910,15 @@ static int swap_read_page(struct swap_map_handle *handle, void *buf,
>  	if (error)
>  		return error;
>  	if (++handle->k >= MAP_PAGE_ENTRIES) {
> -		error = hib_wait_on_bio_chain(bio_chain);
>  		handle->k = 0;
> -		offset = handle->cur->next_swap;
> -		if (!offset)
> +		free_page((unsigned long)handle->maps->map);
> +		tmp = handle->maps;
> +		handle->maps = handle->maps->next;
> +		kfree(tmp);
> +		if (!handle->maps)
>  			release_swap_reader(handle);
> -		else if (!error)
> -			error = hib_bio_read_page(offset, handle->cur, NULL);
> +		else
> +			handle->cur = handle->maps->map;
>  	}
>  	return error;
>  }
> @@ -697,7 +941,7 @@ static int load_image(struct swap_map_handle *handle,
>                        unsigned int nr_to_read)
>  {
>  	unsigned int m;
> -	int error = 0;
> +	int ret = 0;
>  	struct timeval start;
>  	struct timeval stop;
>  	struct bio *bio;
> @@ -713,15 +957,15 @@ static int load_image(struct swap_map_handle *handle,
>  	bio = NULL;
>  	do_gettimeofday(&start);
>  	for ( ; ; ) {
> -		error = snapshot_write_next(snapshot);
> -		if (error <= 0)
> +		ret = snapshot_write_next(snapshot);
> +		if (ret <= 0)
>  			break;
> -		error = swap_read_page(handle, data_of(*snapshot), &bio);
> -		if (error)
> +		ret = swap_read_page(handle, data_of(*snapshot), &bio);
> +		if (ret)
>  			break;
>  		if (snapshot->sync_read)
> -			error = hib_wait_on_bio_chain(&bio);
> -		if (error)
> +			ret = hib_wait_on_bio_chain(&bio);
> +		if (ret)
>  			break;
>  		if (!(nr_pages % m))
>  			printk("\b\b\b\b%3d%%", nr_pages / m);
> @@ -729,17 +973,61 @@ static int load_image(struct swap_map_handle *handle,
>  	}
>  	err2 = hib_wait_on_bio_chain(&bio);
>  	do_gettimeofday(&stop);
> -	if (!error)
> -		error = err2;
> -	if (!error) {
> +	if (!ret)
> +		ret = err2;
> +	if (!ret) {
>  		printk("\b\b\b\bdone\n");
>  		snapshot_write_finalize(snapshot);
>  		if (!snapshot_image_loaded(snapshot))
> -			error = -ENODATA;
> +			ret = -ENODATA;
>  	} else
>  		printk("\n");
>  	swsusp_show_speed(&start, &stop, nr_to_read, "Read");
> -	return error;
> +	return ret;
> +}
> +
> +/**
> + * Structure used for LZO data decompression.
> + */
> +struct dec_data {
> +	struct task_struct *thr;                  /* thread */
> +	atomic_t ready;                           /* ready to start flag */
> +	atomic_t stop;                            /* ready to stop flag */
> +	int ret;                                  /* return code */
> +	wait_queue_head_t go;                     /* start decompression */
> +	wait_queue_head_t done;                   /* decompression done */
> +	size_t unc_len;                           /* uncompressed length */
> +	size_t cmp_len;                           /* compressed length */
> +	unsigned char unc[LZO_UNC_SIZE];          /* uncompressed buffer */
> +	unsigned char cmp[LZO_CMP_SIZE];          /* compressed buffer */
> +};
> +
> +/**
> + * Deompression function that runs in its own thread.
> + */
> +static int lzo_decompress_threadfn(void *data)
> +{
> +	struct dec_data *d = data;
> +
> +	while (1) {
> +		wait_event(d->go, atomic_read(&d->ready) ||
> +		                  kthread_should_stop());
> +		if (kthread_should_stop()) {
> +			d->thr = NULL;
> +			d->ret = -1;
> +			atomic_set(&d->stop, 1);
> +			wake_up(&d->done);
> +			break;
> +		}
> +		atomic_set(&d->ready, 0);
> +
> +		d->unc_len = LZO_UNC_SIZE;
> +		d->ret = lzo1x_decompress_safe(d->cmp + LZO_HEADER, d->cmp_len,
> +		                               d->unc, &d->unc_len);
> +		atomic_set(&d->stop, 1);
> +		wake_up(&d->done);
> +	}
> +	return 0;
>  }
>  
>  /**
> @@ -753,50 +1041,120 @@ static int load_image_lzo(struct swap_map_handle *handle,
>                            unsigned int nr_to_read)
>  {
>  	unsigned int m;
> -	int error = 0;
> +	int ret = 0;
> +	int eof = 0;
>  	struct bio *bio;
>  	struct timeval start;
>  	struct timeval stop;
>  	unsigned nr_pages;
> -	size_t i, off, unc_len, cmp_len;
> -	unsigned char *unc, *cmp, *page[LZO_CMP_PAGES];
> -
> -	for (i = 0; i < LZO_CMP_PAGES; i++) {
> -		page[i] = (void *)__get_free_page(__GFP_WAIT | __GFP_HIGH);
> -		if (!page[i]) {
> -			printk(KERN_ERR "PM: Failed to allocate LZO page\n");
> +	size_t off;
> +	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 char **page = NULL;
> +	struct dec_data *data = NULL;
> +	struct crc_data *crc = NULL;
> +
> +	/*
> +	 * We'll limit the number of threads for decompression to limit memory
> +	 * footprint.
> +	 */
> +	nr_threads = num_online_cpus() - 1;
> +	nr_threads = clamp_val(nr_threads, 1, LZO_THREADS);
> +
> +	page = vmalloc(sizeof(*page) * LZO_READ_PAGES);
> +	if (!page) {
> +		printk(KERN_ERR "PM: Failed to allocate LZO page\n");
> +		ret = -ENOMEM;
> +		goto out_clean;
> +	}
>  
> -			while (i)
> -				free_page((unsigned long)page[--i]);
> +	data = vmalloc(sizeof(*data) * nr_threads);
> +	if (!data) {
> +		printk(KERN_ERR "PM: Failed to allocate LZO data\n");
> +		ret = -ENOMEM;
> +		goto out_clean;
> +	}
> +	for (thr = 0; thr < nr_threads; thr++)
> +		memset(&data[thr], 0, offsetof(struct dec_data, go));
>  
> -			return -ENOMEM;
> +	crc = kmalloc(sizeof(*crc), GFP_KERNEL);
> +	if (!crc) {
> +		printk(KERN_ERR "PM: Failed to allocate crc\n");
> +		ret = -ENOMEM;
> +		goto out_clean;
> +	}
> +	memset(crc, 0, offsetof(struct crc_data, go));
> +
> +	/*
> +	 * Start the decompression threads.
> +	 */
> +	for (thr = 0; thr < nr_threads; thr++) {
> +		init_waitqueue_head(&data[thr].go);
> +		init_waitqueue_head(&data[thr].done);
> +
> +		data[thr].thr = kthread_run(lzo_decompress_threadfn,
> +		                            &data[thr],
> +		                            "image_decompress/%u", thr);
> +		if (IS_ERR(data[thr].thr)) {
> +			data[thr].thr = NULL;
> +			printk(KERN_ERR
> +			       "PM: Cannot start decompression threads\n");
> +			ret = -ENOMEM;
> +			goto out_clean;
>  		}
>  	}
>  
> -	unc = vmalloc(LZO_UNC_SIZE);
> -	if (!unc) {
> -		printk(KERN_ERR "PM: Failed to allocate LZO uncompressed\n");
> -
> -		for (i = 0; i < LZO_CMP_PAGES; i++)
> -			free_page((unsigned long)page[i]);
> -
> -		return -ENOMEM;
> +	/*
> +	 * Start the CRC32 thread.
> +	 */
> +	init_waitqueue_head(&crc->go);
> +	init_waitqueue_head(&crc->done);
> +
> +	handle->crc32 = 0;
> +	crc->crc32 = &handle->crc32;
> +	for (thr = 0; thr < nr_threads; thr++) {
> +		crc->unc[thr] = data[thr].unc;
> +		crc->unc_len[thr] = &data[thr].unc_len;
>  	}
>  
> -	cmp = vmalloc(LZO_CMP_SIZE);
> -	if (!cmp) {
> -		printk(KERN_ERR "PM: Failed to allocate LZO compressed\n");
> +	crc->thr = kthread_run(crc32_threadfn, crc, "image_crc32");
> +	if (IS_ERR(crc->thr)) {
> +		crc->thr = NULL;
> +		printk(KERN_ERR "PM: Cannot start CRC32 thread\n");
> +		ret = -ENOMEM;
> +		goto out_clean;
> +	}
>  
> -		vfree(unc);
> -		for (i = 0; i < LZO_CMP_PAGES; i++)
> -			free_page((unsigned long)page[i]);
> +	/*
> +	 * Adjust number of pages for read buffering, in case we are short.
> +	 */
> +	read_pages = (nr_free_pages() - snapshot_get_image_size()) >> 1;
> +	read_pages = clamp_val(read_pages, LZO_CMP_PAGES, LZO_READ_PAGES);
>  
> -		return -ENOMEM;
> +	for (i = 0; i < read_pages; i++) {
> +		page[i] = (void *)__get_free_page(i < LZO_CMP_PAGES ?
> +		                                  __GFP_WAIT | __GFP_HIGH :
> +		                                  __GFP_WAIT);
> +		if (!page[i]) {
> +			if (i < LZO_CMP_PAGES) {
> +				ring_size = i;
> +				printk(KERN_ERR
> +				       "PM: Failed to allocate LZO pages\n");
> +				ret = -ENOMEM;
> +				goto out_clean;
> +			} else {
> +				break;
> +			}
> +		}
>  	}
> +	want = ring_size = i;
>  
>  	printk(KERN_INFO
> +		"PM: Using %u thread(s) for decompression.\n"
>  		"PM: Loading and decompressing image data (%u pages) ...     ",
> -		nr_to_read);
> +		nr_threads, nr_to_read);
>  	m = nr_to_read / 100;
>  	if (!m)
>  		m = 1;
> @@ -804,85 +1162,189 @@ static int load_image_lzo(struct swap_map_handle *handle,
>  	bio = NULL;
>  	do_gettimeofday(&start);
>  
> -	error = snapshot_write_next(snapshot);
> -	if (error <= 0)
> +	ret = snapshot_write_next(snapshot);
> +	if (ret <= 0)
>  		goto out_finish;
>  
> -	for (;;) {
> -		error = swap_read_page(handle, page[0], NULL); /* sync */
> -		if (error)
> -			break;
> -
> -		cmp_len = *(size_t *)page[0];
> -		if (unlikely(!cmp_len ||
> -		             cmp_len > lzo1x_worst_compress(LZO_UNC_SIZE))) {
> -			printk(KERN_ERR "PM: Invalid LZO compressed length\n");
> -			error = -1;
> -			break;
> +	for(;;) {
> +		for (i = 0; !eof && i < want; i++) {
> +			ret = swap_read_page(handle, page[ring], &bio);
> +			if (ret) {
> +				/*
> +				 * On real read error, finish. On end of data,
> +				 * set EOF flag and just exit the read loop.
> +				 */
> +				if (handle->cur &&
> +				    handle->cur->entries[handle->k]) {
> +					goto out_finish;
> +				} else {
> +					eof = 1;
> +					break;
> +				}
> +			}
> +			if (++ring >= ring_size)
> +				ring = 0;
>  		}
> +		asked += i;
> +		want -= i;
>  
> -		for (off = PAGE_SIZE, i = 1;
> -		     off < LZO_HEADER + cmp_len; off += PAGE_SIZE, i++) {
> -			error = swap_read_page(handle, page[i], &bio);
> -			if (error)
> +		/*
> +		 * We are out of data, wait for some more.
> +		 */
> +		if (!have) {
> +			if (!asked)
> +				break;
> +
> +			ret = hib_wait_on_bio_chain(&bio);
> +			if (ret)
>  				goto out_finish;
> +			have += asked;
> +			asked = 0;
> +			if (eof)
> +				eof = 2;
>  		}
>  
> -		error = hib_wait_on_bio_chain(&bio); /* need all data now */
> -		if (error)
> -			goto out_finish;
> -
> -		for (off = 0, i = 0;
> -		     off < LZO_HEADER + cmp_len; off += PAGE_SIZE, i++) {
> -			memcpy(cmp + off, page[i], PAGE_SIZE);
> +		if (crc->run_threads) {
> +			wait_event(crc->done, atomic_read(&crc->stop));
> +			atomic_set(&crc->stop, 0);
> +			crc->run_threads = 0;
>  		}
>  
> -		unc_len = LZO_UNC_SIZE;
> -		error = lzo1x_decompress_safe(cmp + LZO_HEADER, cmp_len,
> -		                              unc, &unc_len);
> -		if (error < 0) {
> -			printk(KERN_ERR "PM: LZO decompression failed\n");
> -			break;
> +		for (thr = 0; have && thr < nr_threads; thr++) {
> +			data[thr].cmp_len = *(size_t *)page[pg];
> +			if (unlikely(!data[thr].cmp_len ||
> +			             data[thr].cmp_len >
> +			             lzo1x_worst_compress(LZO_UNC_SIZE))) {
> +				printk(KERN_ERR
> +				       "PM: Invalid LZO compressed length\n");
> +				ret = -1;
> +				goto out_finish;
> +			}
> +
> +			need = DIV_ROUND_UP(data[thr].cmp_len + LZO_HEADER,
> +			                    PAGE_SIZE);
> +			if (need > have) {
> +				if (eof > 1) {
> +					ret = -1;
> +					goto out_finish;
> +				}
> +				break;
> +			}
> +
> +			for (off = 0;
> +			     off < LZO_HEADER + data[thr].cmp_len;
> +			     off += PAGE_SIZE) {
> +				memcpy(data[thr].cmp + off,
> +				       page[pg], PAGE_SIZE);
> +				have--;
> +				want++;
> +				if (++pg >= ring_size)
> +					pg = 0;
> +			}
> +
> +			atomic_set(&data[thr].ready, 1);
> +			wake_up(&data[thr].go);
>  		}
>  
> -		if (unlikely(!unc_len ||
> -		             unc_len > LZO_UNC_SIZE ||
> -		             unc_len & (PAGE_SIZE - 1))) {
> -			printk(KERN_ERR "PM: Invalid LZO uncompressed length\n");
> -			error = -1;
> -			break;
> +		/*
> +		 * Wait for more data while we are decompressing.
> +		 */
> +		if (have < LZO_CMP_PAGES && asked) {
> +			ret = hib_wait_on_bio_chain(&bio);
> +			if (ret)
> +				goto out_finish;
> +			have += asked;
> +			asked = 0;
> +			if (eof)
> +				eof = 2;
>  		}
>  
> -		for (off = 0; off < unc_len; off += PAGE_SIZE) {
> -			memcpy(data_of(*snapshot), unc + off, PAGE_SIZE);
> +		for (run_threads = thr, thr = 0; thr < run_threads; thr++) {
> +			wait_event(data[thr].done,
> +			           atomic_read(&data[thr].stop));
> +			atomic_set(&data[thr].stop, 0);
> +
> +			ret = data[thr].ret;
>  
> -			if (!(nr_pages % m))
> -				printk("\b\b\b\b%3d%%", nr_pages / m);
> -			nr_pages++;
> +			if (ret < 0) {
> +				printk(KERN_ERR
> +				       "PM: LZO decompression failed\n");
> +				goto out_finish;
> +			}
>  
> -			error = snapshot_write_next(snapshot);
> -			if (error <= 0)
> +			if (unlikely(!data[thr].unc_len ||
> +			             data[thr].unc_len > LZO_UNC_SIZE ||
> +			             data[thr].unc_len & (PAGE_SIZE - 1))) {
> +				printk(KERN_ERR
> +				       "PM: Invalid LZO uncompressed length\n");
> +				ret = -1;
>  				goto out_finish;
> +			}
> +
> +			for (off = 0;
> +			     off < data[thr].unc_len; off += PAGE_SIZE) {
> +				memcpy(data_of(*snapshot),
> +				       data[thr].unc + off, PAGE_SIZE);
> +
> +				if (!(nr_pages % m))
> +					printk("\b\b\b\b%3d%%", nr_pages / m);
> +				nr_pages++;
> +
> +				ret = snapshot_write_next(snapshot);
> +				if (ret <= 0) {
> +					crc->run_threads = thr + 1;
> +					atomic_set(&crc->ready, 1);
> +					wake_up(&crc->go);
> +					goto out_finish;
> +				}
> +			}
>  		}
> +
> +		crc->run_threads = thr;
> +		atomic_set(&crc->ready, 1);
> +		wake_up(&crc->go);
>  	}
>  
>  out_finish:
> +	if (crc->run_threads) {
> +		wait_event(crc->done, atomic_read(&crc->stop));
> +		atomic_set(&crc->stop, 0);
> +	}
>  	do_gettimeofday(&stop);
> -	if (!error) {
> +	if (!ret) {
>  		printk("\b\b\b\bdone\n");
>  		snapshot_write_finalize(snapshot);
>  		if (!snapshot_image_loaded(snapshot))
> -			error = -ENODATA;
> +			ret = -ENODATA;
> +		if (!ret) {
> +			if (swsusp_header->flags & SF_CRC32_MODE) {
> +				if(handle->crc32 != swsusp_header->crc32) {
> +					printk(KERN_ERR
> +					       "PM: Invalid image CRC32!\n");
> +					ret = -ENODATA;
> +				}
> +			}
> +		}
>  	} else
>  		printk("\n");
>  	swsusp_show_speed(&start, &stop, nr_to_read, "Read");
> -
> -	vfree(cmp);
> -	vfree(unc);
> -	for (i = 0; i < LZO_CMP_PAGES; i++)
> +out_clean:
> +	for (i = 0; i < ring_size; i++)
>  		free_page((unsigned long)page[i]);
> +	if (crc) {
> +		if (crc->thr)
> +			kthread_stop(crc->thr);
> +		kfree(crc);
> +	}
> +	if (data) {
> +		for (thr = 0; thr < nr_threads; thr++)
> +			if (data[thr].thr)
> +				kthread_stop(data[thr].thr);
> +		vfree(data);
> +	}
> +	if (page) vfree(page);
>  
> -	return error;
> +	return ret;
>  }
>  
>  /**
> ---------------------------------------
> 
> 

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