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Date: Tue, 3 Oct 2017 12:40:29 +0200
From: Javier González <jg@...htnvm.io>
To: Hans Holmberg <hans.ml.holmberg@...tronix.com>
Cc: Matias Bjørling <mb@...htnvm.io>,
linux-block@...r.kernel.org, linux-kernel@...r.kernel.org,
Hans Holmberg <hans.holmberg@...xlabs.com>
Subject: Re: [PATCH 8/9] lightnvm: pblk: gc all lines in the pipeline before
exit
> On 3 Oct 2017, at 12.05, Hans Holmberg <hans.ml.holmberg@...tronix.com> wrote:
>
> From: Hans Holmberg <hans.holmberg@...xlabs.com>
>
> Finish garbage collect of the lines that are in the gc pipeline
> before exiting. Ensure that all lines already in in the pipeline
> goes through, from read to write.
>
> Do this by keeping track of how many lines are in the pipeline
> and waiting for that number to reach zero before exiting the gc
> reader task.
>
> Since we're adding a new gc line counter, change the name of
> inflight_gc to read_inflight_gc to make the distinction clear.
>
> Signed-off-by: Hans Holmberg <hans.holmberg@...xlabs.com>
> ---
> drivers/lightnvm/pblk-core.c | 3 +++
> drivers/lightnvm/pblk-gc.c | 31 ++++++++++++++++++++++++-------
> drivers/lightnvm/pblk-sysfs.c | 2 +-
> drivers/lightnvm/pblk.h | 5 ++++-
> 4 files changed, 32 insertions(+), 9 deletions(-)
>
> diff --git a/drivers/lightnvm/pblk-core.c b/drivers/lightnvm/pblk-core.c
> index 15e1e28..e62e6eb 100644
> --- a/drivers/lightnvm/pblk-core.c
> +++ b/drivers/lightnvm/pblk-core.c
> @@ -1463,6 +1463,7 @@ void pblk_line_free(struct pblk *pblk, struct pblk_line *line)
> static void __pblk_line_put(struct pblk *pblk, struct pblk_line *line)
> {
> struct pblk_line_mgmt *l_mg = &pblk->l_mg;
> + struct pblk_gc *gc = &pblk->gc;
>
> spin_lock(&line->lock);
> WARN_ON(line->state != PBLK_LINESTATE_GC);
> @@ -1471,6 +1472,8 @@ static void __pblk_line_put(struct pblk *pblk, struct pblk_line *line)
> pblk_line_free(pblk, line);
> spin_unlock(&line->lock);
>
> + atomic_dec(&gc->pipeline_gc);
> +
> spin_lock(&l_mg->free_lock);
> list_add_tail(&line->list, &l_mg->free_list);
> l_mg->nr_free_lines++;
> diff --git a/drivers/lightnvm/pblk-gc.c b/drivers/lightnvm/pblk-gc.c
> index f343f90..475a13e 100644
> --- a/drivers/lightnvm/pblk-gc.c
> +++ b/drivers/lightnvm/pblk-gc.c
> @@ -234,7 +234,7 @@ static void pblk_gc_line_prepare_ws(struct work_struct *work)
> kfree(invalid_bitmap);
>
> kref_put(&line->ref, pblk_line_put);
> - atomic_dec(&gc->inflight_gc);
> + atomic_dec(&gc->read_inflight_gc);
>
> return;
>
> @@ -249,7 +249,7 @@ static void pblk_gc_line_prepare_ws(struct work_struct *work)
>
> pblk_put_line_back(pblk, line);
> kref_put(&line->ref, pblk_line_put);
> - atomic_dec(&gc->inflight_gc);
> + atomic_dec(&gc->read_inflight_gc);
>
> pr_err("pblk: Failed to GC line %d\n", line->id);
> }
> @@ -268,6 +268,7 @@ static int pblk_gc_line(struct pblk *pblk, struct pblk_line *line)
> line_ws->pblk = pblk;
> line_ws->line = line;
>
> + atomic_inc(&gc->pipeline_gc);
> INIT_WORK(&line_ws->ws, pblk_gc_line_prepare_ws);
> queue_work(gc->gc_reader_wq, &line_ws->ws);
>
> @@ -333,6 +334,7 @@ static bool pblk_gc_should_run(struct pblk_gc *gc, struct pblk_rl *rl)
> void pblk_gc_free_full_lines(struct pblk *pblk)
> {
> struct pblk_line_mgmt *l_mg = &pblk->l_mg;
> + struct pblk_gc *gc = &pblk->gc;
> struct pblk_line *line;
>
> do {
> @@ -353,6 +355,7 @@ void pblk_gc_free_full_lines(struct pblk *pblk)
> list_del(&line->list);
> spin_unlock(&l_mg->gc_lock);
>
> + atomic_inc(&gc->pipeline_gc);
> kref_put(&line->ref, pblk_line_put);
> } while (1);
> }
> @@ -370,12 +373,12 @@ static void pblk_gc_run(struct pblk *pblk)
> struct pblk_line *line;
> struct list_head *group_list;
> bool run_gc;
> - int inflight_gc, gc_group = 0, prev_group = 0;
> + int read_inflight_gc, gc_group = 0, prev_group = 0;
>
> pblk_gc_free_full_lines(pblk);
>
> run_gc = pblk_gc_should_run(&pblk->gc, &pblk->rl);
> - if (!run_gc || (atomic_read(&gc->inflight_gc) >= PBLK_GC_L_QD))
> + if (!run_gc || (atomic_read(&gc->read_inflight_gc) >= PBLK_GC_L_QD))
> return;
>
> next_gc_group:
> @@ -402,14 +405,14 @@ static void pblk_gc_run(struct pblk *pblk)
> list_add_tail(&line->list, &gc->r_list);
> spin_unlock(&gc->r_lock);
>
> - inflight_gc = atomic_inc_return(&gc->inflight_gc);
> + read_inflight_gc = atomic_inc_return(&gc->read_inflight_gc);
> pblk_gc_reader_kick(gc);
>
> prev_group = 1;
>
> /* No need to queue up more GC lines than we can handle */
> run_gc = pblk_gc_should_run(&pblk->gc, &pblk->rl);
> - if (!run_gc || inflight_gc >= PBLK_GC_L_QD)
> + if (!run_gc || read_inflight_gc >= PBLK_GC_L_QD)
> break;
> } while (1);
>
> @@ -470,6 +473,7 @@ static int pblk_gc_writer_ts(void *data)
> static int pblk_gc_reader_ts(void *data)
> {
> struct pblk *pblk = data;
> + struct pblk_gc *gc = &pblk->gc;
>
> while (!kthread_should_stop()) {
> if (!pblk_gc_read(pblk))
> @@ -478,6 +482,18 @@ static int pblk_gc_reader_ts(void *data)
> io_schedule();
> }
>
> +#ifdef CONFIG_NVM_DEBUG
> + pr_info("pblk: flushing gc pipeline, %d lines left\n",
> + atomic_read(&gc->pipeline_gc));
> +#endif
> +
> + do {
> + if (!atomic_read(&gc->pipeline_gc))
> + break;
> +
> + schedule();
> + } while (1);
> +
> return 0;
> }
>
> @@ -581,7 +597,8 @@ int pblk_gc_init(struct pblk *pblk)
> gc->gc_forced = 0;
> gc->gc_enabled = 1;
> gc->w_entries = 0;
> - atomic_set(&gc->inflight_gc, 0);
> + atomic_set(&gc->read_inflight_gc, 0);
> + atomic_set(&gc->pipeline_gc, 0);
>
> /* Workqueue that reads valid sectors from a line and submit them to the
> * GC writer to be recycled.
> diff --git a/drivers/lightnvm/pblk-sysfs.c b/drivers/lightnvm/pblk-sysfs.c
> index 95fb434..cd49e88 100644
> --- a/drivers/lightnvm/pblk-sysfs.c
> +++ b/drivers/lightnvm/pblk-sysfs.c
> @@ -253,7 +253,7 @@ static ssize_t pblk_sysfs_lines(struct pblk *pblk, char *page)
> sz += snprintf(page + sz, PAGE_SIZE - sz,
> "GC: full:%d, high:%d, mid:%d, low:%d, empty:%d, queue:%d\n",
> gc_full, gc_high, gc_mid, gc_low, gc_empty,
> - atomic_read(&pblk->gc.inflight_gc));
> + atomic_read(&pblk->gc.read_inflight_gc));
>
> sz += snprintf(page + sz, PAGE_SIZE - sz,
> "data (%d) cur:%d, left:%d, vsc:%d, s:%d, map:%d/%d (%d)\n",
> diff --git a/drivers/lightnvm/pblk.h b/drivers/lightnvm/pblk.h
> index f76583b..03965da 100644
> --- a/drivers/lightnvm/pblk.h
> +++ b/drivers/lightnvm/pblk.h
> @@ -238,7 +238,10 @@ struct pblk_gc {
> struct timer_list gc_timer;
>
> struct semaphore gc_sem;
> - atomic_t inflight_gc;
> + atomic_t read_inflight_gc; /* Number of lines with inflight GC reads */
> + atomic_t pipeline_gc; /* Number of lines in the GC pipeline -
> + * started reads to finished writes
> + */
> int w_entries;
>
> struct list_head w_list;
> --
> 2.7.4
LGTM.
Reviewed-by: Javier González <javier@...xlabs.com>
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