Hi Jonathan,
On Thu, Feb 9, 2023 at 12:38 PM Jonathan Derrick
<jonathan.derrick@xxxxxxxxx> wrote:
>
> Hi Song,
>
> Any thoughts on this?
I am really sorry that I missed this patch.
>
> On 1/17/2023 5:53 PM, Jonathan Derrick wrote:
> > From: Jon Derrick <jonathan.derrick@xxxxxxxxx>
> >
> > If the bitmap space has enough room, size the I/O for the last bitmap
> > page write to the optimal I/O size for the storage device. The expanded
> > write is checked that it won't overrun the data or metadata.
> >
> > This change helps increase performance by preventing unnecessary
> > device-side read-mod-writes due to non-atomic write unit sizes.
> >
> > Ex biosnoop log. Device lba size 512, optimal size 4k:
> > Before:
> > Time Process PID Device LBA Size Lat
> > 0.843734 md0_raid10 5267 nvme0n1 W 24 3584 1.17
> > 0.843933 md0_raid10 5267 nvme1n1 W 24 3584 1.36
> > 0.843968 md0_raid10 5267 nvme1n1 W 14207939968 4096 0.01
> > 0.843979 md0_raid10 5267 nvme0n1 W 14207939968 4096 0.02
> >
> > After:
> > Time Process PID Device LBA Size Lat
> > 18.374244 md0_raid10 6559 nvme0n1 W 24 4096 0.01
> > 18.374253 md0_raid10 6559 nvme1n1 W 24 4096 0.01
> > 18.374300 md0_raid10 6559 nvme0n1 W 11020272296 4096 0.01
> > 18.374306 md0_raid10 6559 nvme1n1 W 11020272296 4096 0.02
Do we see significant improvements from io benchmarks?
IIUC, fewer future HDDs will use 512B LBA size.We probably don't need
such optimizations in the future.
Thanks,
Song
> >
> > Signed-off-by: Jon Derrick <jonathan.derrick@xxxxxxxxx>
> > ---
> > drivers/md/md-bitmap.c | 27 ++++++++++++++++++---------
> > 1 file changed, 18 insertions(+), 9 deletions(-)
> >
> > diff --git a/drivers/md/md-bitmap.c b/drivers/md/md-bitmap.c
> > index e7cc6ba1b657..569297ea9b99 100644
> > --- a/drivers/md/md-bitmap.c
> > +++ b/drivers/md/md-bitmap.c
> > @@ -220,6 +220,7 @@ static int write_sb_page(struct bitmap *bitmap, struct page *page, int wait)
> > rdev = NULL;
> > while ((rdev = next_active_rdev(rdev, mddev)) != NULL) {
> > int size = PAGE_SIZE;
> > + int optimal_size = PAGE_SIZE;
> > loff_t offset = mddev->bitmap_info.offset;
> >
> > bdev = (rdev->meta_bdev) ? rdev->meta_bdev : rdev->bdev;
> > @@ -228,9 +229,14 @@ static int write_sb_page(struct bitmap *bitmap, struct page *page, int wait)
> > int last_page_size = store->bytes & (PAGE_SIZE-1);
> > if (last_page_size == 0)
> > last_page_size = PAGE_SIZE;
> > - size = roundup(last_page_size,
> > - bdev_logical_block_size(bdev));
> > + size = roundup(last_page_size, bdev_logical_block_size(bdev));
> > + if (bdev_io_opt(bdev) > bdev_logical_block_size(bdev))
> > + optimal_size = roundup(last_page_size, bdev_io_opt(bdev));
> > + else
> > + optimal_size = size;
> > }
> > +
> > +
> > /* Just make sure we aren't corrupting data or
> > * metadata
> > */
> > @@ -246,9 +252,11 @@ static int write_sb_page(struct bitmap *bitmap, struct page *page, int wait)
> > goto bad_alignment;
> > } else if (offset < 0) {
> > /* DATA BITMAP METADATA */
> > - if (offset
> > - + (long)(page->index * (PAGE_SIZE/512))
> > - + size/512 > 0)
> > + loff_t off = offset + (long)(page->index * (PAGE_SIZE/512));
> > + if (size != optimal_size &&
> > + off + optimal_size/512 <= 0)
> > + size = optimal_size;
> > + else if (off + size/512 > 0)
> > /* bitmap runs in to metadata */
> > goto bad_alignment;
> > if (rdev->data_offset + mddev->dev_sectors
> > @@ -257,10 +265,11 @@ static int write_sb_page(struct bitmap *bitmap, struct page *page, int wait)
> > goto bad_alignment;
> > } else if (rdev->sb_start < rdev->data_offset) {
> > /* METADATA BITMAP DATA */
> > - if (rdev->sb_start
> > - + offset
> > - + page->index*(PAGE_SIZE/512) + size/512
> > - > rdev->data_offset)
> > + loff_t off = rdev->sb_start + offset + page->index*(PAGE_SIZE/512);
> > + if (size != optimal_size &&
> > + off + optimal_size/512 <= rdev->data_offset)
> > + size = optimal_size;
> > + else if (off + size/512 > rdev->data_offset)
> > /* bitmap runs in to data */
> > goto bad_alignment;
> > } else {
