From cd67e10ac6997c6d1e1504e3c111b693bfdbc148 Mon Sep 17 00:00:00 2001 From: Minchan Kim Date: Thu, 30 Jan 2014 15:45:52 -0800 Subject: [PATCH] zram: promote zram from staging Zram has lived in staging for a LONG LONG time and have been fixed/improved by many contributors so code is clean and stable now. Of course, there are lots of product using zram in real practice. The major TV companys have used zram as swap since two years ago and recently our production team released android smart phone with zram which is used as swap, too and recently Android Kitkat start to use zram for small memory smart phone. And there was a report Google released their ChromeOS with zram, too and cyanogenmod have been used zram long time ago. And I heard some disto have used zram block device for tmpfs. In addition, I saw many report from many other peoples. For example, Lubuntu start to use it. The benefit of zram is very clear. With my experience, one of the benefit was to remove jitter of video application with backgroud memory pressure. It would be effect of efficient memory usage by compression but more issue is whether swap is there or not in the system. Recent mobile platforms have used JAVA so there are many anonymous pages. But embedded system normally are reluctant to use eMMC or SDCard as swap because there is wear-leveling and latency issues so if we do not use swap, it means we can't reclaim anoymous pages and at last, we could encounter OOM kill. :( Although we have real storage as swap, it was a problem, too. Because it sometime ends up making system very unresponsible caused by slow swap storage performance. Quote from Luigi on Google "Since Chrome OS was mentioned: the main reason why we don't use swap to a disk (rotating or SSD) is because it doesn't degrade gracefully and leads to a bad interactive experience. Generally we prefer to manage RAM at a higher level, by transparently killing and restarting processes. But we noticed that zram is fast enough to be competitive with the latter, and it lets us make more efficient use of the available RAM. " and he announced. http://www.spinics.net/lists/linux-mm/msg57717.html Other uses case is to use zram for block device. Zram is block device so anyone can format the block device and mount on it so some guys on the internet start zram as /var/tmp. http://forums.gentoo.org/viewtopic-t-838198-start-0.html Let's promote zram and enhance/maintain it instead of removing. Signed-off-by: Minchan Kim Reviewed-by: Konrad Rzeszutek Wilk Acked-by: Nitin Gupta Acked-by: Pekka Enberg Cc: Bob Liu Cc: Greg Kroah-Hartman Cc: Hugh Dickins Cc: Jens Axboe Cc: Luigi Semenzato Cc: Mel Gorman Cc: Rik van Riel Cc: Seth Jennings Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- {drivers/staging/zram => Documentation/blockdev}/zram.txt | 0 drivers/block/Kconfig | 2 ++ drivers/block/Makefile | 1 + drivers/{staging => block}/zram/Kconfig | 0 drivers/{staging => block}/zram/Makefile | 0 drivers/{staging => block}/zram/zram_drv.c | 0 drivers/{staging => block}/zram/zram_drv.h | 0 drivers/staging/Kconfig | 2 -- drivers/staging/Makefile | 1 - 9 files changed, 3 insertions(+), 3 deletions(-) rename {drivers/staging/zram => Documentation/blockdev}/zram.txt (100%) rename drivers/{staging => block}/zram/Kconfig (100%) rename drivers/{staging => block}/zram/Makefile (100%) rename drivers/{staging => block}/zram/zram_drv.c (100%) rename drivers/{staging => block}/zram/zram_drv.h (100%) diff --git a/drivers/staging/zram/zram.txt b/Documentation/blockdev/zram.txt similarity index 100% rename from drivers/staging/zram/zram.txt rename to Documentation/blockdev/zram.txt diff --git a/drivers/block/Kconfig b/drivers/block/Kconfig index 9ffa90c6201c..014a1cfc41c5 100644 --- a/drivers/block/Kconfig +++ b/drivers/block/Kconfig @@ -108,6 +108,8 @@ source "drivers/block/paride/Kconfig" source "drivers/block/mtip32xx/Kconfig" +source "drivers/block/zram/Kconfig" + config BLK_CPQ_DA tristate "Compaq SMART2 support" depends on PCI && VIRT_TO_BUS && 0 diff --git a/drivers/block/Makefile b/drivers/block/Makefile index 816d979c3266..02b688d1438d 100644 --- a/drivers/block/Makefile +++ b/drivers/block/Makefile @@ -42,6 +42,7 @@ obj-$(CONFIG_BLK_DEV_PCIESSD_MTIP32XX) += mtip32xx/ obj-$(CONFIG_BLK_DEV_RSXX) += rsxx/ obj-$(CONFIG_BLK_DEV_NULL_BLK) += null_blk.o +obj-$(CONFIG_ZRAM) += zram/ nvme-y := nvme-core.o nvme-scsi.o skd-y := skd_main.o diff --git a/drivers/staging/zram/Kconfig b/drivers/block/zram/Kconfig similarity index 100% rename from drivers/staging/zram/Kconfig rename to drivers/block/zram/Kconfig diff --git a/drivers/staging/zram/Makefile b/drivers/block/zram/Makefile similarity index 100% rename from drivers/staging/zram/Makefile rename to drivers/block/zram/Makefile diff --git a/drivers/staging/zram/zram_drv.c b/drivers/block/zram/zram_drv.c similarity index 100% rename from drivers/staging/zram/zram_drv.c rename to drivers/block/zram/zram_drv.c diff --git a/drivers/staging/zram/zram_drv.h b/drivers/block/zram/zram_drv.h similarity index 100% rename from drivers/staging/zram/zram_drv.h rename to drivers/block/zram/zram_drv.h diff --git a/drivers/staging/Kconfig b/drivers/staging/Kconfig index 120d2fa9e531..040a51525b42 100644 --- a/drivers/staging/Kconfig +++ b/drivers/staging/Kconfig @@ -76,8 +76,6 @@ source "drivers/staging/sep/Kconfig" source "drivers/staging/iio/Kconfig" -source "drivers/staging/zram/Kconfig" - source "drivers/staging/wlags49_h2/Kconfig" source "drivers/staging/wlags49_h25/Kconfig" diff --git a/drivers/staging/Makefile b/drivers/staging/Makefile index cb19d0afa0da..dea056bf7ff2 100644 --- a/drivers/staging/Makefile +++ b/drivers/staging/Makefile @@ -32,7 +32,6 @@ obj-$(CONFIG_VT6656) += vt6656/ obj-$(CONFIG_VME_BUS) += vme/ obj-$(CONFIG_DX_SEP) += sep/ obj-$(CONFIG_IIO) += iio/ -obj-$(CONFIG_ZRAM) += zram/ obj-$(CONFIG_WLAGS49_H2) += wlags49_h2/ obj-$(CONFIG_WLAGS49_H25) += wlags49_h25/ obj-$(CONFIG_FB_SM7XX) += sm7xxfb/