[PATCH 07/10] Increase compressed page size threshold

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From: Nitin Gupta
Date: Monday, August 9, 2010 - 10:26 am

Compression takes much more time than decompression. So, its quite
wasteful in terms of both CPU cycles and memory usage to have a very
low compressed page size threshold and thereby storing such not-so-well
compressible pages as-is (uncompressed). So, increasing it from
PAGE_SIZE/2 to PAGE_SIZE/8*7. A low threshold was useful when we had
"backing swap" support where we could forward such pages to the backing
device (applicable only when zram was used as swap disk).

It is not yet configurable through sysfs but may be exported in future,
along with threshold for average compression ratio.

Signed-off-by: Nitin Gupta <ngupta@vflare.org>
---
 drivers/staging/zram/zram_drv.h |    2 +-
 1 files changed, 1 insertions(+), 1 deletions(-)

diff --git a/drivers/staging/zram/zram_drv.h b/drivers/staging/zram/zram_drv.h
index 65e512d..bcc51ea 100644
--- a/drivers/staging/zram/zram_drv.h
+++ b/drivers/staging/zram/zram_drv.h
@@ -47,7 +47,7 @@ static const unsigned default_disksize_perc_ram = 25;
  * Pages that compress to size greater than this are stored
  * uncompressed in memory.
  */
-static const unsigned max_zpage_size = PAGE_SIZE / 4 * 3;
+static const unsigned max_zpage_size = PAGE_SIZE / 8 * 7;
 
 /*
  * NOTE: max_zpage_size must be less than or equal to:
-- 
1.7.2.1

--
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Messages in current thread:
[PATCH 00/10] zram: various improvements and cleanups, Nitin Gupta, (Mon Aug 9, 10:26 am)
[PATCH 01/10] Replace ioctls with sysfs interface, Nitin Gupta, (Mon Aug 9, 10:26 am)
[PATCH 03/10] Use percpu stats, Nitin Gupta, (Mon Aug 9, 10:26 am)
[PATCH 04/10] Use percpu buffers, Nitin Gupta, (Mon Aug 9, 10:26 am)
[PATCH 06/10] Block discard support, Nitin Gupta, (Mon Aug 9, 10:26 am)
[PATCH 07/10] Increase compressed page size threshold, Nitin Gupta, (Mon Aug 9, 10:26 am)
[PATCH 08/10] Some cleanups, Nitin Gupta, (Mon Aug 9, 10:26 am)
[PATCH 09/10] Update zram documentation, Nitin Gupta, (Mon Aug 9, 10:26 am)
[PATCH 10/10] Document sysfs entries, Nitin Gupta, (Mon Aug 9, 10:26 am)
Re: [PATCH 01/10] Replace ioctls with sysfs interface, Pekka Enberg, (Mon Aug 9, 11:34 am)
Re: [PATCH 03/10] Use percpu stats, Pekka Enberg, (Mon Aug 9, 11:44 am)
Re: [PATCH 04/10] Use percpu buffers, Pekka Enberg, (Mon Aug 9, 11:57 am)
Re: [PATCH 08/10] Some cleanups, Pekka Enberg, (Mon Aug 9, 12:02 pm)
Re: [PATCH 10/10] Document sysfs entries, Pekka Enberg, (Mon Aug 9, 12:02 pm)
Re: [PATCH 06/10] Block discard support, Pekka Enberg, (Mon Aug 9, 12:03 pm)
Re: [PATCH 06/10] Block discard support, Jens Axboe, (Mon Aug 9, 7:23 pm)
Re: [PATCH 03/10] Use percpu stats, Andrew Morton, (Mon Aug 9, 9:34 pm)
Re: [PATCH 04/10] Use percpu buffers, Nitin Gupta, (Mon Aug 9, 9:47 pm)
Re: [PATCH 06/10] Block discard support, Nitin Gupta, (Mon Aug 9, 9:54 pm)
Re: [PATCH 04/10] Use percpu buffers, Pekka Enberg, (Mon Aug 9, 10:05 pm)
Re: [PATCH 04/10] Use percpu buffers, Nitin Gupta, (Mon Aug 9, 10:32 pm)
Re: [PATCH 04/10] Use percpu buffers, Pekka Enberg, (Tue Aug 10, 12:36 am)
Re: [PATCH 06/10] Block discard support, Jens Axboe, (Tue Aug 10, 8:54 am)
Re: [PATCH 03/10] Use percpu stats, Nitin Gupta, (Wed Aug 11, 9:39 am)
Re: [PATCH 03/10] Use percpu stats, Andrew Morton, (Wed Aug 11, 10:18 am)
Re: [PATCH 03/10] Use percpu stats, Christoph Lameter, (Mon Aug 30, 9:20 am)
Re: [PATCH 03/10] Use percpu stats, Nitin Gupta, (Tue Aug 31, 1:31 pm)
Re: [PATCH 03/10] Use percpu stats, Eric Dumazet, (Tue Aug 31, 2:28 pm)
Re: [PATCH 03/10] Use percpu stats, Christoph Lameter, (Tue Aug 31, 2:35 pm)
Re: [PATCH 03/10] Use percpu stats, Eric Dumazet, (Tue Aug 31, 2:41 pm)
Re: [PATCH 01/10] Replace ioctls with sysfs interface, Dave Hansen, (Tue Aug 31, 4:06 pm)
Re: [PATCH 00/10] zram: various improvements and cleanups, Anton Blanchard, (Tue Aug 31, 8:32 pm)
Re: [PATCH 03/10] Use percpu stats, Anton Blanchard, (Tue Aug 31, 8:41 pm)
Re: [PATCH 03/10] Use percpu stats, Anton Blanchard, (Tue Aug 31, 8:51 pm)
Re: [PATCH 03/10] Use percpu stats, Christoph Lameter, (Wed Sep 1, 1:05 pm)
Re: [PATCH 03/10] Use percpu stats, Eric Dumazet, (Wed Sep 1, 1:38 pm)
Re: [PATCH 03/10] Use percpu stats, Christoph Lameter, (Wed Sep 1, 5:34 pm)
Re: [PATCH 03/10] Use percpu stats, Andrew Morton, (Fri Sep 17, 1:59 pm)
Re: OOM panics with zram, Nitin Gupta, (Sun Oct 3, 11:41 am)
Re: OOM panics with zram, Dave Hansen, (Sun Oct 3, 12:27 pm)
Re: OOM panics with zram, Nitin Gupta, (Sun Oct 3, 12:40 pm)
Re: OOM panics with zram, Ed Tomlinson, (Mon Oct 4, 4:08 am)
Re: OOM panics with zram, Greg KH, (Tue Oct 5, 4:43 pm)
Re: OOM panics with zram, Nitin Gupta, (Tue Oct 5, 7:29 pm)
Re: OOM panics with zram, Greg KH, (Tue Oct 5, 7:36 pm)
Re: OOM panics with zram, Nitin Gupta, (Tue Oct 5, 9:30 pm)
Re: OOM panics with zram, Pekka Enberg, (Wed Oct 6, 12:38 am)
Re: OOM panics with zram, Greg KH, (Wed Oct 6, 7:02 am)
Re: OOM panics with zram, Greg KH, (Wed Oct 6, 7:03 am)
Re: OOM panics with zram, Pekka Enberg, (Wed Oct 6, 7:16 am)
Re: OOM panics with zram, Nitin Gupta, (Wed Oct 6, 7:53 am)