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Date: Tue, 21 Oct 2014 16:27:37 +0900 From: karam.lee@....com To: minchan@...nel.org, ngupta@...are.org, linux-kernel@...r.kernel.org Cc: matthew.r.wilcox@...el.com, jmarchan@...hat.com, seungho1.park@....com, "karam.lee" <karam.lee@....com> Subject: [PATCH v3 3/3] zram: implement rw_page operation of zram From: "karam.lee" <karam.lee@....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.lee@....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..696f0b5 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 = 1; + 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 = -ENOMEM; + 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 -- 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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