From: "karam.lee" <karam....@lge.com>
This patch implements rw_page operation for zram block device.
I implemented the feature in zram and tested it.
Test bed was the G2, LG electronic mobile device, whtich has msm8974
processor and 2GB memory.
With a memory allocation test program consuming memory, the system
generates swap.
And operating time of swap_write_page() was measured.
--------------------------------------------------
| | operating time | improvement |
| | (20 runs average) | |
--------------------------------------------------
|with patch | 1061.15 us | +2.4% |
--------------------------------------------------
|without patch| 1087.35 us | |
--------------------------------------------------
Each test(with paged_io,with BIO) result set shows normal distribution
and has equal variance.
I mean the two values are valid result to compare.
I can say operation with paged I/O(without BIO) is faster 2.4% with
confidence level 95%.
Signed-off-by: karam.lee <karam....@lge.com>
---
drivers/block/zram/zram_drv.c | 38 ++++++++++++++++++++++++++++++++++++++
1 file changed, 38 insertions(+)
diff --git a/drivers/block/zram/zram_drv.c b/drivers/block/zram/zram_drv.c
index 4565fdc..8d3086a 100644
--- a/drivers/block/zram/zram_drv.c
+++ b/drivers/block/zram/zram_drv.c
@@ -810,8 +810,46 @@ static void zram_slot_free_notify(struct block_device
*bdev,
atomic64_inc(&zram->stats.notify_free);
}
+static int zram_rw_page(struct block_device *bdev, sector_t sector,
+ struct page *page, int rw)
+{
+ int offset, ret;
+ u32 index;
+ struct zram *zram;
+ struct bio_vec bv;
+
+ zram = bdev->bd_disk->private_data;
+ if (!valid_io_request(zram, sector, PAGE_SIZE)) {
+ atomic64_inc(&zram->stats.invalid_io);
+ ret = -EINVAL;
+ goto out;
+ }
+
+ down_read(&zram->init_lock);
+ if (unlikely(!init_done(zram))) {
+ ret = -EIO;
+ goto out_unlock;
+ }
+
+ index = sector >> SECTORS_PER_PAGE_SHIFT;
+ offset = sector & (SECTORS_PER_PAGE - 1) << SECTOR_SHIFT;
+
+ bv.bv_page = page;
+ bv.bv_len = PAGE_SIZE;
+ bv.bv_offset = 0;
+
+ ret = zram_bvec_rw(zram, &bv, index, offset, rw);
+
+out_unlock:
+ up_read(&zram->init_lock);
+out:
+ page_endio(page, rw, ret);
+ return ret;
+}
+
static const struct block_device_operations zram_devops = {
.swap_slot_free_notify = zram_slot_free_notify,
+ .rw_page = zram_rw_page,
.owner = THIS_MODULE
};
--
1.7.9.5
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