On Thu, Sep 12 2019 at 12:07P -0400,
Mikulas Patocka <mpatocka@xxxxxxxxxx> wrote:
>
>
> On Thu, 12 Sep 2019, Heinz Mauelshagen wrote:
>
> > Mikulas,
> >
> > please use list_move instead of list_del/list_add pairs.
> >
> > Heinz
>
> OK. Here I resend it.
>
>
>
> From: Mikulas Patocka <mpatocka@xxxxxxxxxx>
>
> This patch introduces a global cache replacement (instead of per-client
> cleanup).
>
> If one bufio client uses the cache heavily and another client is not using
> it, we want to let the first client use most of the cache. The old
> algorithm would partition the cache equally betwen the clients and that is
> inoptimal.
>
> For cache replacement, we use the clock algorithm because it doesn't
> require taking any lock when the buffer is accessed.
>
> Signed-off-by: Mikulas Patocka <mpatocka@xxxxxxxxxx>
I'd like to fold in this cleanup if you're OK with it.
Rather use a main control structure for the loop rather than gotos.
You OK with this?
diff --git a/drivers/md/dm-bufio.c b/drivers/md/dm-bufio.c
index 8c6edec8a838..2d519c223562 100644
--- a/drivers/md/dm-bufio.c
+++ b/drivers/md/dm-bufio.c
@@ -230,7 +230,6 @@ static LIST_HEAD(dm_bufio_all_clients);
*/
static DEFINE_MUTEX(dm_bufio_clients_lock);
-
static struct workqueue_struct *dm_bufio_wq;
static struct delayed_work dm_bufio_cleanup_old_work;
static struct work_struct dm_bufio_replacement_work;
@@ -1827,62 +1826,60 @@ static void do_global_cleanup(struct work_struct *w)
struct dm_bufio_client *current_client;
struct dm_buffer *b;
unsigned spinlock_hold_count;
- unsigned long threshold = dm_bufio_cache_size - dm_bufio_cache_size / DM_BUFIO_LOW_WATERMARK_RATIO;
+ unsigned long threshold = dm_bufio_cache_size -
+ dm_bufio_cache_size / DM_BUFIO_LOW_WATERMARK_RATIO;
unsigned long loops = global_num * 2;
mutex_lock(&dm_bufio_clients_lock);
-reacquire_spinlock:
- cond_resched();
+ while (1) {
+ cond_resched();
- spin_lock(&global_spinlock);
- if (unlikely(dm_bufio_current_allocated <= threshold))
- goto exit;
+ spin_lock(&global_spinlock);
+ if (unlikely(dm_bufio_current_allocated <= threshold))
+ break;
- spinlock_hold_count = 0;
+ spinlock_hold_count = 0;
get_next:
- if (!loops--)
- goto exit;
- if (unlikely(list_empty(&global_queue)))
- goto exit;
- b = list_entry(global_queue.prev, struct dm_buffer, global_list);
-
- if (b->accessed) {
- b->accessed = 0;
- list_move(&b->global_list, &global_queue);
- if (likely(++spinlock_hold_count < 16)) {
- goto get_next;
- }
- spin_unlock(&global_spinlock);
- goto reacquire_spinlock;
- }
-
- current_client = b->c;
- if (unlikely(current_client != locked_client)) {
- if (locked_client)
- dm_bufio_unlock(locked_client);
+ if (!loops--)
+ break;
+ if (unlikely(list_empty(&global_queue)))
+ break;
+ b = list_entry(global_queue.prev, struct dm_buffer, global_list);
- if (!dm_bufio_trylock(current_client)) {
+ if (b->accessed) {
+ b->accessed = 0;
+ list_move(&b->global_list, &global_queue);
+ if (likely(++spinlock_hold_count < 16))
+ goto get_next;
spin_unlock(&global_spinlock);
- dm_bufio_lock(current_client);
- locked_client = current_client;
- goto reacquire_spinlock;
+ continue;
}
- locked_client = current_client;
- }
+ current_client = b->c;
+ if (unlikely(current_client != locked_client)) {
+ if (locked_client)
+ dm_bufio_unlock(locked_client);
- spin_unlock(&global_spinlock);
+ if (!dm_bufio_trylock(current_client)) {
+ spin_unlock(&global_spinlock);
+ dm_bufio_lock(current_client);
+ locked_client = current_client;
+ continue;
+ }
+
+ locked_client = current_client;
+ }
- if (unlikely(!__try_evict_buffer(b, GFP_KERNEL))) {
- spin_lock(&global_spinlock);
- list_move(&b->global_list, &global_queue);
spin_unlock(&global_spinlock);
- }
- goto reacquire_spinlock;
+ if (unlikely(!__try_evict_buffer(b, GFP_KERNEL))) {
+ spin_lock(&global_spinlock);
+ list_move(&b->global_list, &global_queue);
+ spin_unlock(&global_spinlock);
+ }
+ }
-exit:
spin_unlock(&global_spinlock);
if (locked_client)
--
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