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Subject[PATCH]: Compress hibernation image with LZO (in-kernel)
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This patch speeds up hibernate/thaw operations (in kernel ones) by
compressing the pages using LZO. Tests on my ThinkPad T510 show that
hibernation times can be cut by the factor of about 4 for an image of
around 1 GB (from about a minute down to about 15 seconds).

I'm not really familiar with kernel internals, so many of the things in
this patch could be very, very wrong. But go easy - this is essentially
the first time I've attempted something like this.

PS. I'm not on the list, so please CC me if you'd like to contact me.

--
Bojan
diff --git a/kernel/power/Kconfig b/kernel/power/Kconfig
index ca6066a..cb57eb9 100644
--- a/kernel/power/Kconfig
+++ b/kernel/power/Kconfig
@@ -137,6 +137,8 @@ config SUSPEND_FREEZER
config HIBERNATION
bool "Hibernation (aka 'suspend to disk')"
depends on PM && SWAP && ARCH_HIBERNATION_POSSIBLE
+ select LZO_COMPRESS
+ select LZO_DECOMPRESS
select SUSPEND_NVS if HAS_IOMEM
---help---
Enable the suspend to disk (STD) functionality, which is usually
diff --git a/kernel/power/swap.c b/kernel/power/swap.c
index b0bb217..36dfdfb 100644
--- a/kernel/power/swap.c
+++ b/kernel/power/swap.c
@@ -24,6 +24,7 @@
#include <linux/swapops.h>
#include <linux/pm.h>
#include <linux/slab.h>
+#include <linux/lzo.h>

#include "power.h"

@@ -357,6 +358,12 @@ static int swap_writer_finish(struct swap_map_handle *handle,
return error;
}

+#define LZO_HEADER sizeof(size_t)
+#define LZO_UNC_PAGES 64
+#define LZO_UNC_SIZE (LZO_UNC_PAGES * PAGE_SIZE)
+#define LZO_CMP_PAGES DIV_ROUND_UP(lzo1x_worst_compress(LZO_UNC_SIZE) + \
+ LZO_HEADER, PAGE_SIZE)
+#define LZO_CMP_SIZE (LZO_CMP_PAGES * PAGE_SIZE)
/**
* save_image - save the suspend image data
*/
@@ -372,6 +379,39 @@ static int save_image(struct swap_map_handle *handle,
struct bio *bio;
struct timeval start;
struct timeval stop;
+ size_t ul, cl;
+ unsigned char *unc, *cmp;
+ void *wrk, *page;
+
+ page = (void *)__get_free_page(__GFP_WAIT | __GFP_HIGH);
+ if (!page) {
+ printk(KERN_ERR "PM: Failed to allocate LZO page\n");
+ return -ENOMEM;
+ }
+
+ 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;
+ }
+
+ 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;
+ }
+
+ 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;
+ }

printk(KERN_INFO "PM: Saving image data pages (%u pages) ... ",
nr_to_write);
@@ -382,16 +422,48 @@ static int save_image(struct swap_map_handle *handle,
bio = NULL;
do_gettimeofday(&start);
while (1) {
- ret = snapshot_read_next(snapshot);
- if (ret <= 0)
+ for (ul = 0; ul < LZO_UNC_SIZE; ul += PAGE_SIZE) {
+ ret = snapshot_read_next(snapshot);
+ if (ret < 0)
+ goto out_finish;
+
+ if (ret == 0)
+ break;
+
+ memcpy(unc + ul, data_of(*snapshot), PAGE_SIZE);
+
+ if (!(nr_pages % m))
+ printk(KERN_CONT "\b\b\b\b%3d%%", nr_pages / m);
+ nr_pages++;
+ }
+
+ if (ul == 0)
+ break;
+
+ ret = lzo1x_1_compress(unc, ul, cmp + LZO_HEADER, &cl, wrk);
+ if (ret < 0) {
+ printk(KERN_ERR "PM: LZO compression failed\n");
break;
- ret = swap_write_page(handle, data_of(*snapshot), &bio);
- if (ret)
+ }
+
+ if (unlikely(cl == 0 || LZO_HEADER + cl > LZO_CMP_SIZE)) {
+ printk(KERN_ERR "PM: Invalid LZO length\n");
+ ret = -1;
break;
- if (!(nr_pages % m))
- printk(KERN_CONT "\b\b\b\b%3d%%", nr_pages / m);
- nr_pages++;
+ }
+
+ *(size_t *)cmp = cl;
+
+ for (ul = 0; ul < LZO_HEADER + cl; ul += PAGE_SIZE) {
+ memcpy(page, cmp + ul, PAGE_SIZE);
+
+ ret = swap_write_page(handle, page, &bio);
+ if (ret)
+ goto out_finish;
+ }
}
+
+out_finish:
err2 = hib_wait_on_bio_chain(&bio);
do_gettimeofday(&stop);
if (!ret)
@@ -401,6 +473,12 @@ static int save_image(struct swap_map_handle *handle,
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);
+
return ret;
}

@@ -416,7 +494,8 @@ static int enough_swap(unsigned int nr_pages)
unsigned int free_swap = count_swap_pages(root_swap, 1);

pr_debug("PM: Free swap pages: %u\n", free_swap);
- return free_swap > nr_pages + PAGES_FOR_IO;
+ return free_swap >
+ (nr_pages * LZO_CMP_PAGES) / LZO_UNC_PAGES + PAGES_FOR_IO;
}

/**
@@ -550,6 +629,30 @@ static int load_image(struct swap_map_handle *handle,
struct bio *bio;
int err2;
unsigned nr_pages;
+ size_t ul, cl;
+ unsigned char *unc, *cmp;
+ void *page;
+
+ page = (void *)__get_free_page(__GFP_WAIT | __GFP_HIGH);
+ if (!page) {
+ printk(KERN_ERR "PM: Failed to allocate LZO page\n");
+ return -ENOMEM;
+ }
+
+ unc = vmalloc(LZO_UNC_SIZE);
+ if (!unc) {
+ printk(KERN_ERR "PM: Failed to allocate LZO uncompressed\n");
+ free_page((unsigned long)page);
+ return -ENOMEM;
+ }
+
+ cmp = vmalloc(LZO_CMP_SIZE);
+ if (!cmp) {
+ printk(KERN_ERR "PM: Failed to allocate LZO compressed\n");
+ vfree(unc);
+ free_page((unsigned long)page);
+ return -ENOMEM;
+ }

printk(KERN_INFO "PM: Loading image data pages (%u pages) ... ",
nr_to_read);
@@ -559,21 +662,52 @@ static int load_image(struct swap_map_handle *handle,
nr_pages = 0;
bio = NULL;
do_gettimeofday(&start);
+
+ error = snapshot_write_next(snapshot);
+ if (error <= 0)
+ goto out_finish;
+
for ( ; ; ) {
- error = snapshot_write_next(snapshot);
- if (error <= 0)
- break;
- error = swap_read_page(handle, data_of(*snapshot), &bio);
+ error = swap_read_page(handle, page, NULL); /* sync */
if (error)
break;
- if (snapshot->sync_read)
- error = hib_wait_on_bio_chain(&bio);
- if (error)
+ memcpy(cmp, page, PAGE_SIZE);
+
+ cl = *(size_t *)cmp;
+ if (unlikely(cl == 0 || LZO_HEADER + cl > LZO_CMP_SIZE)) {
+ printk(KERN_ERR "PM: Invalid LZO length\n");
+ error = -1;
break;
- if (!(nr_pages % m))
- printk("\b\b\b\b%3d%%", nr_pages / m);
- nr_pages++;
+ }
+
+ for (ul = PAGE_SIZE; ul < LZO_HEADER + cl; ul += PAGE_SIZE) {
+ error = swap_read_page(handle, page, NULL); /* sync */
+ if (error)
+ goto out_finish;
+ memcpy(cmp + ul, page, PAGE_SIZE);
+ }
+
+ ul = LZO_UNC_SIZE;
+ error = lzo1x_decompress_safe(cmp + LZO_HEADER, cl, unc, &ul);
+ if (error < 0) {
+ printk(KERN_ERR "PM: LZO decompression failed\n");
+ break;
+ }
+
+ for (cl = 0; cl < ul; cl += PAGE_SIZE) {
+ memcpy(data_of(*snapshot), unc + cl, 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;
+ }
}
+
+out_finish:
err2 = hib_wait_on_bio_chain(&bio);
do_gettimeofday(&stop);
if (!error)
@@ -586,6 +720,11 @@ static int load_image(struct swap_map_handle *handle,
} else
printk("\n");
swsusp_show_speed(&start, &stop, nr_to_read, "Read");
+
+ vfree(cmp);
+ vfree(unc);
+ free_page((unsigned long)page);
+
return error;
}
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