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Date:	Wed, 5 Oct 2011 00:07:00 +0200
From:	"Rafael J. Wysocki" <rjw@...k.pl>
To:	Bojan Smojver <bojan@...ursive.com>
Cc:	linux-kernel@...r.kernel.org,
	Linux PM mailing list <linux-pm@...ts.linux-foundation.org>
Subject: Re: [PATCH v8]: Improve performance of LZO/plain hibernation

On Friday, September 30, 2011, Bojan Smojver wrote:
> Pekka was right - there is no measurable difference in performance,
> whether we bind threads to specific CPUs or not. So, I dropped that, it
> is not required and makes code simpler.
> 
> Other than that, just some code simplifications, variable name cleanups
> and buglet removals.
> 
> Note that I changed the subject to reflect the fact that
> hibernation/thaw without compression also benefits from the patch, from
> the improved I/O.
> 
> ---------------------------------------
> Use threads for LZO compression/decompression on hibernate/thaw.
> Improve buffering on hibernate/thaw.
> v8
> 
> In my testing, this improved write/read speed by a factor of 2 to 3.
> 
> Signed-off-by: Bojan Smojver <bojan@...ursive.com>

Applied to linux-pm/linux-next.

Thanks,
Rafael


> ---
>  kernel/power/swap.c |  628 ++++++++++++++++++++++++++++++++++++++-------------
>  1 files changed, 466 insertions(+), 162 deletions(-)
> 
> diff --git a/kernel/power/swap.c b/kernel/power/swap.c
> index 7c97c3a..d692842 100644
> --- a/kernel/power/swap.c
> +++ b/kernel/power/swap.c
> @@ -27,6 +27,9 @@
>  #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 "power.h"
>  
> @@ -43,8 +46,7 @@
>   *	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 +56,11 @@ 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
> @@ -61,9 +68,11 @@ 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;
>  };
>  
>  struct swsusp_header {
> @@ -245,6 +254,7 @@ 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 +264,17 @@ 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 +311,8 @@ static int get_swap_writer(struct swap_map_handle *handle)
>  		goto err_rel;
>  	}
>  	handle->k = 0;
> +	handle->nr_free_pages = nr_free_pages();
> +	handle->written = 0;
>  	handle->first_sector = handle->cur_swap;
>  	return 0;
>  err_rel:
> @@ -316,20 +336,23 @@ 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 (++handle->written > (handle->nr_free_pages >> 1)) {
> +		error = hib_wait_on_bio_chain(bio_chain);
> +		if (error)
> +			goto out;
> +		handle->written = 0;
> +	}
>   out:
>  	return error;
>  }
> @@ -372,6 +395,13 @@ 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 * 4)
> +
> +
>  /**
>   *	save_image - save the suspend image data
>   */
> @@ -419,6 +449,50 @@ static int save_image(struct swap_map_handle *handle,
>  	return ret;
>  }
>  
> +/**
> + * 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 +511,65 @@ 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, thr, run_threads, nr_threads;
> +	unsigned char *page = NULL;
> +	struct cmp_data *data = NULL;
> +
> +	/*
> +	 * We'll limit the number of threads for compression to limit memory
> +	 * footprint.
> +	 */
> +	nr_threads = num_online_cpus() - 1;
> +	if (nr_threads > LZO_THREADS)
> +		nr_threads = LZO_THREADS;
> +	else if (nr_threads < 1)
> +		nr_threads = 1;
>  
>  	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;
>  	}
> -
> -	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;
> +	for (thr = 0; thr < nr_threads; thr++)
> +		memset(&data[thr], 0, offsetof(struct cmp_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/%zu", thr);
> +		if (IS_ERR(data[thr].thr)) {
> +			nr_threads = thr;
> +			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();
>  
>  	printk(KERN_INFO
> +		"PM: Using %zu 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;
> @@ -480,54 +577,75 @@ 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;
> -		}
> -
> -		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;
> +			}
>  		}
>  	}
>  
> @@ -541,11 +659,13 @@ out_finish:
>  	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:
> +	for (thr = 0; thr < nr_threads; thr++) {
> +		if (data[thr].thr)
> +			kthread_stop(data[thr].thr);
> +	}
> +	if (data) vfree(data);
> +	if (page) free_page((unsigned long)page);
>  
>  	return ret;
>  }
> @@ -625,31 +745,65 @@ out_finish:
>  
>  static void release_swap_reader(struct swap_map_handle *handle)
>  {
> +	struct swap_map_page_list *tmp;
> +
>  	if (handle->cur)
>  		free_page((unsigned long)handle->cur);
> +	while (handle->maps) {
> +		if (handle->maps->map)
> +			free_page((unsigned long)handle->maps->map);
> +		tmp = handle->maps;
> +		handle->maps = handle->maps->next;
> +		vfree(tmp);
> +	}
>  	handle->cur = NULL;
> +	handle->maps = NULL;
>  }
>  
>  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 = vmalloc(sizeof(*handle->maps));
> +		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 +812,7 @@ 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 +823,15 @@ 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;
> +		vfree(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;
>  }
> @@ -743,6 +900,50 @@ static int load_image(struct swap_map_handle *handle,
>  }
>  
>  /**
> + * 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;
> +}
> +
> +/**
>   * load_image_lzo - Load compressed image data and decompress them with LZO.
>   * @handle: Swap map handle to use for loading data.
>   * @snapshot: Image to copy uncompressed data into.
> @@ -754,49 +955,81 @@ static int load_image_lzo(struct swap_map_handle *handle,
>  {
>  	unsigned int m;
>  	int error = 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");
> -
> -			while (i)
> -				free_page((unsigned long)page[--i]);
> -
> -			return -ENOMEM;
> -		}
> +	size_t i, off, thr, run_threads, nr_threads;
> +	size_t ring = 0, pg = 0, ring_size = 0, have = 0, want, need, asked = 0;
> +	unsigned char **page = NULL;
> +	struct dec_data *data = NULL;
> +
> +	/*
> +	 * We'll limit the number of threads for decompression to limit memory
> +	 * footprint.
> +	 */
> +	nr_threads = num_online_cpus() - 1;
> +	if (nr_threads > LZO_THREADS)
> +		nr_threads = LZO_THREADS;
> +	else if (nr_threads < 1)
> +		nr_threads = 1;
> +
> +	page = vmalloc(sizeof(*page) * LZO_READ_PAGES);
> +	if (!page) {
> +		printk(KERN_ERR "PM: Failed to allocate LZO page\n");
> +		error = -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;
> +	data = vmalloc(sizeof(*data) * nr_threads);
> +	if (!data) {
> +		printk(KERN_ERR "PM: Failed to allocate LZO data\n");
> +		error = -ENOMEM;
> +		goto out_clean;
> +	}
> +	for (thr = 0; thr < nr_threads; thr++)
> +		memset(&data[thr], 0, offsetof(struct dec_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/%zu", thr);
> +		if (IS_ERR(data[thr].thr)) {
> +			nr_threads = thr;
> +			printk(KERN_ERR
> +			       "PM: Cannot start decompression threads\n");
> +			error = -ENOMEM;
> +			goto out_clean;
> +		}
>  	}
>  
> -	cmp = vmalloc(LZO_CMP_SIZE);
> -	if (!cmp) {
> -		printk(KERN_ERR "PM: Failed to allocate LZO compressed\n");
> -
> -		vfree(unc);
> -		for (i = 0; i < LZO_CMP_PAGES; i++)
> -			free_page((unsigned long)page[i]);
> -
> -		return -ENOMEM;
> +	for (i = 0; i < LZO_READ_PAGES; i++) {
> +		page[i] = (void *)__get_free_page(__GFP_WAIT | __GFP_HIGH);
> +		if (!page[i]) {
> +			if (i < LZO_CMP_PAGES) {
> +				ring_size = i;
> +				printk(KERN_ERR
> +				       "PM: Failed to allocate LZO pages\n");
> +				error = -ENOMEM;
> +				goto out_clean;
> +			} else {
> +				break;
> +			}
> +		}
>  	}
> +	want = ring_size = i;
>  
>  	printk(KERN_INFO
> +		"PM: Using %zu 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;
> @@ -808,61 +1041,128 @@ static int load_image_lzo(struct swap_map_handle *handle,
>  	if (error <= 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++) {
> +			error = swap_read_page(handle, page[ring], &bio);
> +			if (error) {
> +				/*
> +				 * 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);
> +		/*
> +		 * We are out of data, wait for some more.
> +		 */
> +		if (!have) {
> +			if (!asked)
> +				break;
> +
> +			error = hib_wait_on_bio_chain(&bio);
>  			if (error)
>  				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 (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");
> +				error = -1;
> +				goto out_finish;
> +			}
>  
> -		for (off = 0, i = 0;
> -		     off < LZO_HEADER + cmp_len; off += PAGE_SIZE, i++) {
> -			memcpy(cmp + off, page[i], PAGE_SIZE);
> -		}
> +			need = DIV_ROUND_UP(data[thr].cmp_len + LZO_HEADER,
> +			                    PAGE_SIZE);
> +			if (need > have) {
> +				if (eof > 1) {
> +					error = -1;
> +					goto out_finish;
> +				}
> +				break;
> +			}
>  
> -		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 (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) {
> +			error = hib_wait_on_bio_chain(&bio);
> +			if (error)
> +				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);
>  
> -			if (!(nr_pages % m))
> -				printk("\b\b\b\b%3d%%", nr_pages / m);
> -			nr_pages++;
> +			error = data[thr].ret;
>  
> -			error = snapshot_write_next(snapshot);
> -			if (error <= 0)
> +			if (error < 0) {
> +				printk(KERN_ERR
> +				       "PM: LZO decompression failed\n");
>  				goto out_finish;
> +			}
> +
> +			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");
> +				error = -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++;
> +
> +				error = snapshot_write_next(snapshot);
> +				if (error <= 0)
> +					goto out_finish;
> +			}
>  		}
>  	}
>  
> @@ -876,11 +1176,15 @@ out_finish:
>  	} 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]);
> +	for (thr = 0; thr < nr_threads; thr++) {
> +		if (data[thr].thr)
> +			kthread_stop(data[thr].thr);
> +	}
> +	if (data) vfree(data);
> +	if (page) vfree(page);
>  
>  	return error;
>  }
> ---------------------------------------
> 
> 

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