在 2024/06/04 11:05, libaokun@xxxxxxxxxxxxxxx 写道:
From: Baokun Li <libaokun1@xxxxxxxxxx>
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 <libaokun1@xxxxxxxxxx>
LGTM
Reviewed-by: Yu Kuai <yukuai3@xxxxxxxxxx>
---
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;
