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PM: hibernate: make compression threads configurable 

The number of compression/decompression threads has a direct impact on
hibernate image generation and resume latency. Using more threads can
reduce overall resume time, but on systems with fewer CPU cores it may
also introduce contention and reduce efficiency.

Performance was evaluated on an 8-core ARM system, averaged over 10 runs:

    Threads  Hibernate(s)  Resume(s)
    --------------------------------
       3         12.14       18.86
       4         12.28       17.48
       5         11.09       16.77
       6         11.08       16.44

With 5–6 threads, resume latency improves by approximately 12% compared
to the default 3-thread configuration, with negligible impact on
hibernate time.

Introduce a new kernel parameter `hibernate_compression_threads=` that
allows users and integrators to tune the number of
compression/decompression threads at boot. This provides a way to
balance performance and CPU utilization across a wide range of hardware
without recompiling the kernel.

Signed-off-by: Xueqin Luo <luoxueqin@kylinos.cn>
Link: https://patch.msgid.link/f24b3ca6416e230a515a154ed4c121d72a7e05a6.1761046167.git.luoxueqin@kylinos.cn
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
This commit is contained in:
Xueqin Luo 2025-10-21 19:37:27 +08:00 committed by Rafael J. Wysocki
parent e114e2eb7e
commit 090bf5a0f4
2 changed files with 31 additions and 4 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

10
Documentation/admin-guide/kernel-parameters.txt
View File

@ -1907,6 +1907,16 @@
/sys/power/pm_test). Only available when CONFIG_PM_DEBUG /sys/power/pm_test). Only available when CONFIG_PM_DEBUG
is set. Default value is 5. is set. Default value is 5.
hibernate_compression_threads=
[HIBERNATION]
Set the number of threads used for compressing or decompressing
hibernation images.
Format: <integer>
Default: 3
Minimum: 1
Example: hibernate_compression_threads=4
highmem=nn[KMG] [KNL,BOOT,EARLY] forces the highmem zone to have an exact highmem=nn[KMG] [KNL,BOOT,EARLY] forces the highmem zone to have an exact
size of <nn>. This works even on boxes that have no size of <nn>. This works even on boxes that have no
highmem otherwise. This also works to reduce highmem highmem otherwise. This also works to reduce highmem

23
kernel/power/swap.c
View File

@ -519,8 +519,9 @@ static int swap_writer_finish(struct swap_map_handle *handle,
CMP_HEADER, PAGE_SIZE) CMP_HEADER, PAGE_SIZE)
#define CMP_SIZE (CMP_PAGES * PAGE_SIZE) #define CMP_SIZE (CMP_PAGES * PAGE_SIZE)
/* Maximum number of threads for compression/decompression. */ /* Default number of threads for compression/decompression. */
#define CMP_THREADS 3 #define CMP_THREADS 3
static unsigned int hibernate_compression_threads = CMP_THREADS;
/* Minimum/maximum number of pages for read buffering. */ /* Minimum/maximum number of pages for read buffering. */
#define CMP_MIN_RD_PAGES 1024 #define CMP_MIN_RD_PAGES 1024
@ -741,7 +742,7 @@ static int save_compressed_image(struct swap_map_handle *handle,
* footprint. * footprint.
*/ */
nr_threads = num_online_cpus() - 1; nr_threads = num_online_cpus() - 1;
nr_threads = clamp_val(nr_threads, 1, CMP_THREADS); nr_threads = clamp_val(nr_threads, 1, hibernate_compression_threads);
page = (void *)__get_free_page(GFP_NOIO | __GFP_HIGH); page = (void *)__get_free_page(GFP_NOIO | __GFP_HIGH);
if (!page) { if (!page) {
@ -1257,7 +1258,7 @@ static int load_compressed_image(struct swap_map_handle *handle,
* footprint. * footprint.
*/ */
nr_threads = num_online_cpus() - 1; nr_threads = num_online_cpus() - 1;
nr_threads = clamp_val(nr_threads, 1, CMP_THREADS); nr_threads = clamp_val(nr_threads, 1, hibernate_compression_threads);
page = vmalloc_array(CMP_MAX_RD_PAGES, sizeof(*page)); page = vmalloc_array(CMP_MAX_RD_PAGES, sizeof(*page));
if (!page) { if (!page) {
@ -1697,3 +1698,19 @@ static int __init swsusp_header_init(void)
} }
core_initcall(swsusp_header_init); core_initcall(swsusp_header_init);
static int __init hibernate_compression_threads_setup(char *str)
{
int rc = kstrtouint(str, 0, &hibernate_compression_threads);
if (rc)
return rc;
if (hibernate_compression_threads < 1)
hibernate_compression_threads = CMP_THREADS;
return 1;
}
__setup("hibernate_compression_threads=", hibernate_compression_threads_setup);