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author | Javier González <javier@javigon.com> | 2019-02-11 13:25:08 +0100 |
---|---|---|
committer | Jens Axboe <axboe@kernel.dk> | 2019-02-11 08:18:08 -0700 |
commit | b4cdc4260edf7e03d8b6fabb88aec2cdda95917e (patch) | |
tree | 60a43e88ec0f1f66c94843b4e209b782347478d2 /drivers/lightnvm/pblk-rl.c | |
parent | aa8759d80a755cb32f1707b360a265f3695770ef (diff) | |
download | linux-b4cdc4260edf7e03d8b6fabb88aec2cdda95917e.tar.bz2 |
lightnvm: pblk: prevent stall due to wb threshold
In order to respect mw_cuinits, pblk's write buffer maintains a
backpointer to protect data not yet persisted; when writing to the write
buffer, this backpointer defines a threshold that pblk's rate-limiter
enforces.
On small PU configurations, the following scenarios might take place: (i)
the threshold is larger than the write buffer and (ii) the threshold is
smaller than the write buffer, but larger than the maximun allowed
split bio - 256KB at this moment (Note that writes are not always
split - we only do this when we the size of the buffer is smaller
than the buffer). In both cases, pblk's rate-limiter prevents the I/O to
be written to the buffer, thus stalling.
This patch fixes the original backpointer implementation by considering
the threshold both on buffer creation and on the rate-limiters path,
when bio_split is triggered (case (ii) above).
Fixes: 766c8ceb16fc ("lightnvm: pblk: guarantee that backpointer is respected on writer stall")
Signed-off-by: Javier González <javier@javigon.com>
Reviewed-by: Hans Holmberg <hans.holmberg@cnexlabs.com>
Signed-off-by: Matias Bjørling <mb@lightnvm.io>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Diffstat (limited to 'drivers/lightnvm/pblk-rl.c')
-rw-r--r-- | drivers/lightnvm/pblk-rl.c | 5 |
1 files changed, 2 insertions, 3 deletions
diff --git a/drivers/lightnvm/pblk-rl.c b/drivers/lightnvm/pblk-rl.c index 76116d5f78e4..b014957dde0b 100644 --- a/drivers/lightnvm/pblk-rl.c +++ b/drivers/lightnvm/pblk-rl.c @@ -207,7 +207,7 @@ void pblk_rl_free(struct pblk_rl *rl) del_timer(&rl->u_timer); } -void pblk_rl_init(struct pblk_rl *rl, int budget) +void pblk_rl_init(struct pblk_rl *rl, int budget, int threshold) { struct pblk *pblk = container_of(rl, struct pblk, rl); struct nvm_tgt_dev *dev = pblk->dev; @@ -217,7 +217,6 @@ void pblk_rl_init(struct pblk_rl *rl, int budget) int sec_meta, blk_meta; unsigned int rb_windows; - /* Consider sectors used for metadata */ sec_meta = (lm->smeta_sec + lm->emeta_sec[0]) * l_mg->nr_free_lines; blk_meta = DIV_ROUND_UP(sec_meta, geo->clba); @@ -234,7 +233,7 @@ void pblk_rl_init(struct pblk_rl *rl, int budget) /* To start with, all buffer is available to user I/O writers */ rl->rb_budget = budget; rl->rb_user_max = budget; - rl->rb_max_io = budget >> 1; + rl->rb_max_io = threshold ? (budget - threshold) : (budget - 1); rl->rb_gc_max = 0; rl->rb_state = PBLK_RL_HIGH; |