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| author | Vinayak Menon <vinmenon@codeaurora.org> | 2015-02-25 19:43:59 +0530 |
|---|---|---|
| committer | Simon Shields <keepcalm444@gmail.com> | 2016-06-12 21:20:18 +1000 |
| commit | a6ce37fb73dce407da9d7d1d03408602be84177c (patch) | |
| tree | 85ca3a46532a4f2683cb4eab40130ad5707a094e /drivers/block | |
| parent | d997b41417d94c22baaabd8d84a6a4f1e2e93fb9 (diff) | |
| download | kernel_samsung_smdk4412-a6ce37fb73dce407da9d7d1d03408602be84177c.zip kernel_samsung_smdk4412-a6ce37fb73dce407da9d7d1d03408602be84177c.tar.gz kernel_samsung_smdk4412-a6ce37fb73dce407da9d7d1d03408602be84177c.tar.bz2 | |
mm: swap: don't delay swap free for fast swap devices
There are couple of issues with swapcache usage when ZRAM is used
as swap device.
1) Kernel does a swap readahead which can be around 6 to 8 pages
depending on total ram, which is not required for zram since
accesses are fast.
2) Kernel delays the freeing up of swapcache expecting a later hit,
which again is useless in the case of zram.
3) This is not related to swapcache, but zram usage itself.
As mentioned in (2) kernel delays freeing of swapcache, but along with
that it delays zram compressed page free also. i.e. there can be 2 copies,
though one is compressed.
This patch addresses these issues using two new flags
QUEUE_FLAG_FAST and SWP_FAST, to indicate that accesses to the device
will be fast and cheap, and instructs the swap layer to free up
swap space agressively, and not to do read ahead.
Change-Id: I5d2d5176a5f9420300bb2f843f6ecbdb25ea80e4
Signed-off-by: Vinayak Menon <vinmenon@codeaurora.org>
Signed-off-by: D. Andrei Măceș <dmaces@nd.edu>
Conflicts:
include/linux/blkdev.h
include/linux/swap.h
mm/swap_state.c
mm/swapfile.c
Conflicts:
include/linux/blkdev.h
Diffstat (limited to 'drivers/block')
| -rw-r--r-- | drivers/block/zram/zram_drv.c | 1 |
1 files changed, 1 insertions, 0 deletions
diff --git a/drivers/block/zram/zram_drv.c b/drivers/block/zram/zram_drv.c index 803e7a2..7040165 100644 --- a/drivers/block/zram/zram_drv.c +++ b/drivers/block/zram/zram_drv.c @@ -936,6 +936,7 @@ static int create_device(struct zram *zram, int device_id) zram->disk->private_data = zram; snprintf(zram->disk->disk_name, 16, "zram%d", device_id); + __set_bit(QUEUE_FLAG_FAST, &zram->queue->queue_flags); /* Actual capacity set using syfs (/sys/block/zram<id>/disksize */ set_capacity(zram->disk, 0); /* zram devices sort of resembles non-rotational disks */ |