On 12/6/24 05:55, Alexander Atanasov wrote:
Currently lock is taken once for all pios submitted(code block),
move it to protect only the list insertion (data).
The goal is to reduce lock contention on the deferred lock as
it is in the top of lock stats.
https://virtuozzo.atlassian.net/browse/VSTOR-91820
Signed-off-by: Alexander Atanasov <alexander.atana...@virtuozzo.com>
---
drivers/md/dm-ploop-map.c | 8 ++++----
1 file changed, 4 insertions(+), 4 deletions(-)
diff --git a/drivers/md/dm-ploop-map.c b/drivers/md/dm-ploop-map.c
index 4b9e000e0f98..a0fe92a592a1 100644
--- a/drivers/md/dm-ploop-map.c
+++ b/drivers/md/dm-ploop-map.c
@@ -340,8 +340,9 @@ static void ploop_dispatch_pio(struct ploop *ploop, struct
pio *pio,
bool *is_data, bool *is_flush)
{
struct list_head *list = &ploop->pios[pio->queue_list_id];
+ unsigned long flags;
- lockdep_assert_held(&ploop->deferred_lock);
+ lockdep_assert_not_held(&ploop->deferred_lock);
WARN_ON_ONCE(pio->queue_list_id >= PLOOP_LIST_COUNT);
if (pio->queue_list_id == PLOOP_LIST_FLUSH)
@@ -349,23 +350,22 @@ static void ploop_dispatch_pio(struct ploop *ploop,
struct pio *pio,
else
*is_data = true;
+ spin_lock_irqsave(&ploop->deferred_lock, flags);
list_add_tail(&pio->list, list);
+ spin_unlock_irqrestore(&ploop->deferred_lock, flags);
This patch can be merged to "[RFC PATCH vz9 v6 10/62] dm-ploop: convert
the rest of the lists to use llist variant".
Also I think that having one lock around the whole loop introduces much
less lock contention than doing multiple take/release on each iteration
of the loop.
}
void ploop_dispatch_pios(struct ploop *ploop, struct pio *pio,
struct list_head *pio_list)
{
bool is_data = false, is_flush = false;
- unsigned long flags;
- spin_lock_irqsave(&ploop->deferred_lock, flags);
if (pio)
ploop_dispatch_pio(ploop, pio, &is_data, &is_flush);
if (pio_list) {
while ((pio = ploop_pio_list_pop(pio_list)) != NULL)
ploop_dispatch_pio(ploop, pio, &is_data, &is_flush);
}
- spin_unlock_irqrestore(&ploop->deferred_lock, flags);
if (is_data)
queue_work(ploop->wq, &ploop->worker);
--
Best regards, Tikhomirov Pavel
Senior Software Developer, Virtuozzo.
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