On Fri, Jun 22, 2018 at 11:17 AM Matias Bjørling <mb@xxxxxxxxxxx> wrote:
>
> On 06/18/2018 07:56 PM, Heiner Litz wrote:
> > In the read path, partial reads are currently performed synchronously
> > which affects performance for workloads that generate many partial
> > reads. This patch adds an asynchronous partial read path as well as
> > the required partial read ctx.
> >
> > Signed-off-by: Heiner Litz <hlitz@xxxxxxxx>
> > ---
> > drivers/lightnvm/pblk-read.c | 183 ++++++++++++++++++++++++++++---------------
> > drivers/lightnvm/pblk.h | 10 +++
> > 2 files changed, 130 insertions(+), 63 deletions(-)
> >
> > diff --git a/drivers/lightnvm/pblk-read.c b/drivers/lightnvm/pblk-read.c
> > index 6e93c48..828df98 100644
> > --- a/drivers/lightnvm/pblk-read.c
> > +++ b/drivers/lightnvm/pblk-read.c
> > @@ -231,74 +231,36 @@ static void pblk_end_io_read(struct nvm_rq *rqd)
> > __pblk_end_io_read(pblk, rqd, true);
> > }
> >
> > -static int pblk_partial_read(struct pblk *pblk, struct nvm_rq *rqd,
> > - struct bio *orig_bio, unsigned int bio_init_idx,
> > - unsigned long *read_bitmap)
> > +static void pblk_end_partial_read(struct nvm_rq *rqd)
> > {
> > - struct pblk_sec_meta *meta_list = rqd->meta_list;
> > - struct bio *new_bio;
> > + struct pblk *pblk = rqd->private;
> > + struct pblk_g_ctx *r_ctx = nvm_rq_to_pdu(rqd);
> > + struct pblk_pr_ctx *pr_ctx = r_ctx->private;
> > + struct bio *new_bio = rqd->bio;
> > + struct bio *bio = pr_ctx->orig_bio;
> > struct bio_vec src_bv, dst_bv;
> > - void *ppa_ptr = NULL;
> > - void *src_p, *dst_p;
> > - dma_addr_t dma_ppa_list = 0;
> > - __le64 *lba_list_mem, *lba_list_media;
> > - int nr_secs = rqd->nr_ppas;
> > + struct pblk_sec_meta *meta_list = rqd->meta_list;
> > + int bio_init_idx = pr_ctx->bio_init_idx;
> > + unsigned long *read_bitmap = &pr_ctx->bitmap;
> > + int nr_secs = pr_ctx->orig_nr_secs;
> > int nr_holes = nr_secs - bitmap_weight(read_bitmap, nr_secs);
> > - int i, ret, hole;
> > -
> > - /* Re-use allocated memory for intermediate lbas */
> > - lba_list_mem = (((void *)rqd->ppa_list) + pblk_dma_ppa_size);
> > - lba_list_media = (((void *)rqd->ppa_list) + 2 * pblk_dma_ppa_size);
> > -
> > - new_bio = bio_alloc(GFP_KERNEL, nr_holes);
> > -
> > - if (pblk_bio_add_pages(pblk, new_bio, GFP_KERNEL, nr_holes))
> > - goto fail_add_pages;
> > -
> > - if (nr_holes != new_bio->bi_vcnt) {
> > - pr_err("pblk: malformed bio\n");
> > - goto fail;
> > - }
> > -
> > - for (i = 0; i < nr_secs; i++)
> > - lba_list_mem[i] = meta_list[i].lba;
> > -
> > - new_bio->bi_iter.bi_sector = 0; /* internal bio */
> > - bio_set_op_attrs(new_bio, REQ_OP_READ, 0);
> > -
> > - rqd->bio = new_bio;
> > - rqd->nr_ppas = nr_holes;
> > - rqd->flags = pblk_set_read_mode(pblk, PBLK_READ_RANDOM);
> > -
> > - if (unlikely(nr_holes == 1)) {
> > - ppa_ptr = rqd->ppa_list;
> > - dma_ppa_list = rqd->dma_ppa_list;
> > - rqd->ppa_addr = rqd->ppa_list[0];
> > - }
> > -
> > - ret = pblk_submit_io_sync(pblk, rqd);
> > - if (ret) {
> > - bio_put(rqd->bio);
> > - pr_err("pblk: sync read IO submission failed\n");
> > - goto fail;
> > - }
> > -
> > - if (rqd->error) {
> > - atomic_long_inc(&pblk->read_failed);
> > -#ifdef CONFIG_NVM_PBLK_DEBUG
> > - pblk_print_failed_rqd(pblk, rqd, rqd->error);
> > -#endif
> > - }
> > + __le64 *lba_list_mem, *lba_list_media;
> > + void *src_p, *dst_p;
> > + int hole, i;
> >
> > if (unlikely(nr_holes == 1)) {
> > struct ppa_addr ppa;
> >
> > ppa = rqd->ppa_addr;
> > - rqd->ppa_list = ppa_ptr;
> > - rqd->dma_ppa_list = dma_ppa_list;
> > + rqd->ppa_list = pr_ctx->ppa_ptr;
> > + rqd->dma_ppa_list = pr_ctx->dma_ppa_list;
> > rqd->ppa_list[0] = ppa;
> > }
> >
> > + /* Re-use allocated memory for intermediate lbas */
> > + lba_list_mem = (((void *)rqd->ppa_list) + pblk_dma_ppa_size);
> > + lba_list_media = (((void *)rqd->ppa_list) + 2 * pblk_dma_ppa_size);
> > +
> > for (i = 0; i < nr_secs; i++) {
> > lba_list_media[i] = meta_list[i].lba;
> > meta_list[i].lba = lba_list_mem[i];
> > @@ -316,7 +278,7 @@ static int pblk_partial_read(struct pblk *pblk, struct nvm_rq *rqd,
> > meta_list[hole].lba = lba_list_media[i];
> >
> > src_bv = new_bio->bi_io_vec[i++];
> > - dst_bv = orig_bio->bi_io_vec[bio_init_idx + hole];
> > + dst_bv = bio->bi_io_vec[bio_init_idx + hole];
> >
> > src_p = kmap_atomic(src_bv.bv_page);
> > dst_p = kmap_atomic(dst_bv.bv_page);
> > @@ -334,19 +296,107 @@ static int pblk_partial_read(struct pblk *pblk, struct nvm_rq *rqd,
> > } while (hole < nr_secs);
> >
> > bio_put(new_bio);
> > + kfree(pr_ctx);
> >
> > /* restore original request */
> > rqd->bio = NULL;
> > rqd->nr_ppas = nr_secs;
> >
> > + bio_endio(bio);
> > __pblk_end_io_read(pblk, rqd, false);
> > - return NVM_IO_DONE;
> > +}
> >
> > -fail:
> > - /* Free allocated pages in new bio */
> > +static int pblk_setup_partial_read(struct pblk *pblk, struct nvm_rq *rqd,
> > + unsigned int bio_init_idx,
> > + unsigned long *read_bitmap,
> > + int nr_holes)
> > +{
> > + struct pblk_sec_meta *meta_list = rqd->meta_list;
> > + struct pblk_g_ctx *r_ctx = nvm_rq_to_pdu(rqd);
> > + struct pblk_pr_ctx *pr_ctx;
> > + struct bio *new_bio, *bio = r_ctx->private;
> > + __le64 *lba_list_mem;
> > + int nr_secs = rqd->nr_ppas;
> > + int i;
> > +
> > + /* Re-use allocated memory for intermediate lbas */
> > + lba_list_mem = (((void *)rqd->ppa_list) + pblk_dma_ppa_size);
> > +
> > + new_bio = bio_alloc(GFP_KERNEL, nr_holes);
>
>
> new_bio can return NULL.
see Jens's email
>
> > +
> > + if (pblk_bio_add_pages(pblk, new_bio, GFP_KERNEL, nr_holes))
> > + goto fail;
>
> goto bio_put?
do you only want the label to be changed? sure
> > +
> > + if (nr_holes != new_bio->bi_vcnt) {
> > + pr_err("pblk: malformed bio\n");
>
> I don't think there is a need for an error message here. In which case
> would this happen?
This is taken over from the original partial read path. Maybe Javier
knows why it was put in there in the first place.
>
> > + goto fail_pages;
> > + }
>
> goto free_pages?
sure I can change the label
>
> > +
> > + pr_ctx = kmalloc(sizeof(struct pblk_pr_ctx), GFP_KERNEL);
> > + if (!pr_ctx)
> > + goto fail_pages;
> > +
> > + for (i = 0; i < nr_secs; i++)
> > + lba_list_mem[i] = meta_list[i].lba;
> > +
> > + new_bio->bi_iter.bi_sector = 0; /* internal bio */
> > + bio_set_op_attrs(new_bio, REQ_OP_READ, 0);
> > +
> > + rqd->bio = new_bio;
> > + rqd->nr_ppas = nr_holes;
> > + rqd->flags = pblk_set_read_mode(pblk, PBLK_READ_RANDOM);
> > +
> > + pr_ctx->ppa_ptr = NULL;
> > + pr_ctx->orig_bio = bio;
> > + pr_ctx->bitmap = *read_bitmap;
> > + pr_ctx->bio_init_idx = bio_init_idx;
> > + pr_ctx->orig_nr_secs = nr_secs;
> > + r_ctx->private = pr_ctx;
> > +
> > + if (unlikely(nr_holes == 1)) {
> > + pr_ctx->ppa_ptr = rqd->ppa_list;
> > + pr_ctx->dma_ppa_list = rqd->dma_ppa_list;
> > + rqd->ppa_addr = rqd->ppa_list[0];
> > + }
> > + return 0;
> > +
> > +fail_pages:
> > pblk_bio_free_pages(pblk, new_bio, 0, new_bio->bi_vcnt);
> > -fail_add_pages:
> > +fail:
> > + bio_put(new_bio);
> > +
> > + return -ENOMEM;
> > +}
> > +
> > +static int pblk_partial_read_bio(struct pblk *pblk, struct nvm_rq *rqd,
> > + unsigned int bio_init_idx,
> > + unsigned long *read_bitmap, int nr_secs)
> > +{
> > + int nr_holes;
> > + int ret;
> > +
> > + nr_holes = nr_secs - bitmap_weight(read_bitmap, nr_secs);
> > +
> > + if (pblk_setup_partial_read(pblk, rqd, bio_init_idx, read_bitmap,
> > + nr_holes))
> > + return NVM_IO_ERR;
> > +
> > + rqd->end_io = pblk_end_partial_read;
> > +
> > + ret = pblk_submit_io(pblk, rqd);
> > + if (ret) {
> > + bio_put(rqd->bio);
> > + pr_err("pblk: partial read IO submission failed\n");
> > + goto err;
> > + }
> > +
> > + return NVM_IO_OK;
> > +
> > +err:
> > pr_err("pblk: failed to perform partial read\n");
> > +
> > + /* Free allocated pages in new bio */
> > + pblk_bio_free_pages(pblk, rqd->bio, 0, rqd->bio->bi_vcnt);
> > __pblk_end_io_read(pblk, rqd, false);
> > return NVM_IO_ERR;
> > }
> > @@ -480,8 +530,15 @@ int pblk_submit_read(struct pblk *pblk, struct bio *bio)
> > /* The read bio request could be partially filled by the write buffer,
> > * but there are some holes that need to be read from the drive.
> > */
> > - return pblk_partial_read(pblk, rqd, bio, bio_init_idx, &read_bitmap);
> > + ret = pblk_partial_read_bio(pblk, rqd, bio_init_idx, &read_bitmap,
> > + nr_secs);
> > + if (ret)
> > + goto fail_meta_free;
> > +
> > + return NVM_IO_OK;
> >
> > +fail_meta_free:
> > + nvm_dev_dma_free(dev->parent, rqd->meta_list, rqd->dma_meta_list);
> > fail_rqd_free:
> > pblk_free_rqd(pblk, rqd, PBLK_READ);
> > return ret;
> > diff --git a/drivers/lightnvm/pblk.h b/drivers/lightnvm/pblk.h
> > index c072955..1c7ac06 100644
> > --- a/drivers/lightnvm/pblk.h
> > +++ b/drivers/lightnvm/pblk.h
> > @@ -119,6 +119,16 @@ struct pblk_g_ctx {
> > u64 lba;
> > };
> >
> > +/* partial read context */
> > +struct pblk_pr_ctx {
> > + struct bio *orig_bio;
> > + unsigned long bitmap;
>
> Guarantees that this is at least 32bit, but this should be at least 64
> bit right?
>
> > + unsigned int orig_nr_secs;
> > + unsigned int bio_init_idx;
> > + void *ppa_ptr;
> > + dma_addr_t dma_ppa_list;
> > +};
> > +
> > /* Pad context */
> > struct pblk_pad_rq {
> > struct pblk *pblk;
> >
>
