On Tue, Oct 21, 2014 at 03:57:29PM +0200, Jerome Marchand wrote:
> On 10/21/2014 09:27 AM, karam....@lge.com wrote:
> > 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..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;
>
> Small nitpick, but why do you initialize ret to 1? It doesn't seem to be
> ever used (nor is 1 a valid return value AFAICT).
>
> It otherwise looks good.
>
> Acked-by: Jerome Marchand <jmarc...@redhat.com>
>
Thank you for reply. I agree with your opinion.
It was my mistake to initialize ret to 1.
I will resend the fixed version.
> > + 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
> > };
> >
> >
>
>
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