On Thu, Sep 12 2019 at 12:07P -0400, Mikulas Patocka <[email protected]> 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 <[email protected]> > > 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 <[email protected]> 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) -- dm-devel mailing list [email protected] https://www.redhat.com/mailman/listinfo/dm-devel
