From: Baokun Li <[email protected]>
Now we avoid throttling swap writes by determining whether the current
process is kswapd (aka current_is_kswapd()), but swap writes can come
from either kswapd or direct reclaim, so the swap writes from direct
reclaim will still be throttled.
When a process holds a lock to allocate a free page, and enters direct
reclaim because there is no free memory, then it might trigger a hung
due to the wbt throttling that causes other processes to fail to get
the lock.
Both kswapd and direct reclaim set the REQ_SWAP flag, so use REQ_SWAP
instead of current_is_kswapd() to avoid throttling swap writes. Also
renamed WBT_KSWAPD to WBT_SWAP and WBT_RWQ_KSWAPD to WBT_RWQ_SWAP.
Signed-off-by: Baokun Li <[email protected]>
---
block/blk-wbt.c | 18 +++++++++---------
1 file changed, 9 insertions(+), 9 deletions(-)
diff --git a/block/blk-wbt.c b/block/blk-wbt.c
index 64472134dd26..aaacf2f5b223 100644
--- a/block/blk-wbt.c
+++ b/block/blk-wbt.c
@@ -37,7 +37,7 @@
enum wbt_flags {
WBT_TRACKED = 1, /* write, tracked for throttling */
WBT_READ = 2, /* read */
- WBT_KSWAPD = 4, /* write, from kswapd */
+ WBT_SWAP = 4, /* write, from swap_writepage() */
WBT_DISCARD = 8, /* discard */
WBT_NR_BITS = 4, /* number of bits */
@@ -45,7 +45,7 @@ enum wbt_flags {
enum {
WBT_RWQ_BG = 0,
- WBT_RWQ_KSWAPD,
+ WBT_RWQ_SWAP,
WBT_RWQ_DISCARD,
WBT_NUM_RWQ,
};
@@ -172,8 +172,8 @@ static bool wb_recent_wait(struct rq_wb *rwb)
static inline struct rq_wait *get_rq_wait(struct rq_wb *rwb,
enum wbt_flags wb_acct)
{
- if (wb_acct & WBT_KSWAPD)
- return &rwb->rq_wait[WBT_RWQ_KSWAPD];
+ if (wb_acct & WBT_SWAP)
+ return &rwb->rq_wait[WBT_RWQ_SWAP];
else if (wb_acct & WBT_DISCARD)
return &rwb->rq_wait[WBT_RWQ_DISCARD];
@@ -528,7 +528,7 @@ static bool close_io(struct rq_wb *rwb)
time_before(now, rwb->last_comp + HZ / 10);
}
-#define REQ_HIPRIO (REQ_SYNC | REQ_META | REQ_PRIO)
+#define REQ_HIPRIO (REQ_SYNC | REQ_META | REQ_PRIO | REQ_SWAP)
static inline unsigned int get_limit(struct rq_wb *rwb, blk_opf_t opf)
{
@@ -539,13 +539,13 @@ static inline unsigned int get_limit(struct rq_wb *rwb, blk_opf_t opf)
/*
* At this point we know it's a buffered write. If this is
- * kswapd trying to free memory, or REQ_SYNC is set, then
+ * swap trying to free memory, or REQ_SYNC is set, then
* it's WB_SYNC_ALL writeback, and we'll use the max limit for
* that. If the write is marked as a background write, then use
* the idle limit, or go to normal if we haven't had competing
* IO for a bit.
*/
- if ((opf & REQ_HIPRIO) || wb_recent_wait(rwb) || current_is_kswapd())
+ if ((opf & REQ_HIPRIO) || wb_recent_wait(rwb))
limit = rwb->rq_depth.max_depth;
else if ((opf & REQ_BACKGROUND) || close_io(rwb)) {
/*
@@ -622,8 +622,8 @@ static enum wbt_flags bio_to_wbt_flags(struct rq_wb *rwb, struct bio *bio)
if (bio_op(bio) == REQ_OP_READ) {
flags = WBT_READ;
} else if (wbt_should_throttle(bio)) {
- if (current_is_kswapd())
- flags |= WBT_KSWAPD;
+ if (bio->bi_opf & REQ_SWAP)
+ flags |= WBT_SWAP;
if (bio_op(bio) == REQ_OP_DISCARD)
flags |= WBT_DISCARD;
flags |= WBT_TRACKED;
--
2.39.2
?? 2024/06/04 11:05, [email protected] ะด??:
> From: Baokun Li <[email protected]>
>
> Now we avoid throttling swap writes by determining whether the current
> process is kswapd (aka current_is_kswapd()), but swap writes can come
> from either kswapd or direct reclaim, so the swap writes from direct
> reclaim will still be throttled.
>
> When a process holds a lock to allocate a free page, and enters direct
> reclaim because there is no free memory, then it might trigger a hung
> due to the wbt throttling that causes other processes to fail to get
> the lock.
>
> Both kswapd and direct reclaim set the REQ_SWAP flag, so use REQ_SWAP
> instead of current_is_kswapd() to avoid throttling swap writes. Also
> renamed WBT_KSWAPD to WBT_SWAP and WBT_RWQ_KSWAPD to WBT_RWQ_SWAP.
>
> Signed-off-by: Baokun Li <[email protected]>
LGTM
Reviewed-by: Yu Kuai <[email protected]>
> ---
> block/blk-wbt.c | 18 +++++++++---------
> 1 file changed, 9 insertions(+), 9 deletions(-)
>
> diff --git a/block/blk-wbt.c b/block/blk-wbt.c
> index 64472134dd26..aaacf2f5b223 100644
> --- a/block/blk-wbt.c
> +++ b/block/blk-wbt.c
> @@ -37,7 +37,7 @@
> enum wbt_flags {
> WBT_TRACKED = 1, /* write, tracked for throttling */
> WBT_READ = 2, /* read */
> - WBT_KSWAPD = 4, /* write, from kswapd */
> + WBT_SWAP = 4, /* write, from swap_writepage() */
> WBT_DISCARD = 8, /* discard */
>
> WBT_NR_BITS = 4, /* number of bits */
> @@ -45,7 +45,7 @@ enum wbt_flags {
>
> enum {
> WBT_RWQ_BG = 0,
> - WBT_RWQ_KSWAPD,
> + WBT_RWQ_SWAP,
> WBT_RWQ_DISCARD,
> WBT_NUM_RWQ,
> };
> @@ -172,8 +172,8 @@ static bool wb_recent_wait(struct rq_wb *rwb)
> static inline struct rq_wait *get_rq_wait(struct rq_wb *rwb,
> enum wbt_flags wb_acct)
> {
> - if (wb_acct & WBT_KSWAPD)
> - return &rwb->rq_wait[WBT_RWQ_KSWAPD];
> + if (wb_acct & WBT_SWAP)
> + return &rwb->rq_wait[WBT_RWQ_SWAP];
> else if (wb_acct & WBT_DISCARD)
> return &rwb->rq_wait[WBT_RWQ_DISCARD];
>
> @@ -528,7 +528,7 @@ static bool close_io(struct rq_wb *rwb)
> time_before(now, rwb->last_comp + HZ / 10);
> }
>
> -#define REQ_HIPRIO (REQ_SYNC | REQ_META | REQ_PRIO)
> +#define REQ_HIPRIO (REQ_SYNC | REQ_META | REQ_PRIO | REQ_SWAP)
>
> static inline unsigned int get_limit(struct rq_wb *rwb, blk_opf_t opf)
> {
> @@ -539,13 +539,13 @@ static inline unsigned int get_limit(struct rq_wb *rwb, blk_opf_t opf)
>
> /*
> * At this point we know it's a buffered write. If this is
> - * kswapd trying to free memory, or REQ_SYNC is set, then
> + * swap trying to free memory, or REQ_SYNC is set, then
> * it's WB_SYNC_ALL writeback, and we'll use the max limit for
> * that. If the write is marked as a background write, then use
> * the idle limit, or go to normal if we haven't had competing
> * IO for a bit.
> */
> - if ((opf & REQ_HIPRIO) || wb_recent_wait(rwb) || current_is_kswapd())
> + if ((opf & REQ_HIPRIO) || wb_recent_wait(rwb))
> limit = rwb->rq_depth.max_depth;
> else if ((opf & REQ_BACKGROUND) || close_io(rwb)) {
> /*
> @@ -622,8 +622,8 @@ static enum wbt_flags bio_to_wbt_flags(struct rq_wb *rwb, struct bio *bio)
> if (bio_op(bio) == REQ_OP_READ) {
> flags = WBT_READ;
> } else if (wbt_should_throttle(bio)) {
> - if (current_is_kswapd())
> - flags |= WBT_KSWAPD;
> + if (bio->bi_opf & REQ_SWAP)
> + flags |= WBT_SWAP;
> if (bio_op(bio) == REQ_OP_DISCARD)
> flags |= WBT_DISCARD;
> flags |= WBT_TRACKED;
>