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Date: Sat, 17 Mar 2012 21:57:28 +0100 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]: Lower the amount of pages used for buffering on hibernation Hi, On Saturday, March 17, 2012, Bojan Smojver wrote: > Hi Rafael, > > The patch below reduces the amount of pages that can used by hibernation > code for buffering. Previously, we would take half of what was available > as a starting point, now only a quarter. And, we clamp the value to an > absolute maximum, just to be sure. > > Also, the calculation of the maximum number of pages used for buffering > does not depend on the size of the sector type, which it inadvertently > did before. > > In my testing, this had negligible effect on performance, but may > provide more pages to other kernel needs during hibernation. Looks good, please prepare a signed-off version. Thanks, Rafael > --------------------------------------- > kernel/power/swap.c | 15 +++++++++++---- > 1 files changed, 11 insertions(+), 4 deletions(-) > > diff --git a/kernel/power/swap.c b/kernel/power/swap.c > index 8742fd0..6212351 100644 > --- a/kernel/power/swap.c > +++ b/kernel/power/swap.c > @@ -51,6 +51,9 @@ > > #define MAP_PAGE_ENTRIES (PAGE_SIZE / sizeof(sector_t) - 1) > > +/* Maximum number of pages for write buffering. */ > +#define BUF_WRITE_PAGES (1 << 15) > + > struct swap_map_page { > sector_t entries[MAP_PAGE_ENTRIES]; > sector_t next_swap; > @@ -316,7 +319,9 @@ 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->nr_free_pages = nr_free_pages() >> 2; > + handle->nr_free_pages = clamp_val(handle->nr_free_pages, > + 1, BUF_WRITE_PAGES); > handle->written = 0; > handle->first_sector = handle->cur_swap; > return 0; > @@ -404,7 +409,7 @@ static int swap_writer_finish(struct swap_map_handle *handle, > #define LZO_THREADS 3 > > /* Maximum number of pages for read buffering. */ > -#define LZO_READ_PAGES (MAP_PAGE_ENTRIES * 8) > +#define LZO_READ_PAGES (1 << 12) > > > /** > @@ -618,7 +623,9 @@ 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->nr_free_pages = nr_free_pages() >> 1; > + handle->nr_free_pages = nr_free_pages() >> 2; > + handle->nr_free_pages = clamp_val(handle->nr_free_pages, > + 1, BUF_WRITE_PAGES); > > /* > * Start the CRC32 thread. > @@ -1130,7 +1137,7 @@ static int load_image_lzo(struct swap_map_handle *handle, > /* > * Adjust number of pages for read buffering, in case we are short. > */ > - read_pages = (nr_free_pages() - snapshot_get_image_size()) >> 1; > + read_pages = (nr_free_pages() - snapshot_get_image_size()) >> 2; > read_pages = clamp_val(read_pages, LZO_CMP_PAGES, LZO_READ_PAGES); > > for (i = 0; i < read_pages; i++) { > --------------------------------------- > > -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@...r.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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