linux-kernel - [PATCH 01/17] block, bfq: properly mark bfqq remained idle

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Date:   Sun, 19 Feb 2023 18:42:53 +0800
From:   Kemeng Shi <shikemeng@...weicloud.com>
To:     paolo.valente@...aro.org, axboe@...nel.dk, jack@...e.cz
Cc:     linux-block@...r.kernel.org, linux-kernel@...r.kernel.org,
        shikemeng@...weicloud.com
Subject: [PATCH 01/17] block, bfq: properly mark bfqq remained idle

Bfqq activation will try to recover the "service hole" of bfqq which may
issues requests greedily while remained idle for other reasons: CPU high
load, bfqq not enjoying idling, I/O throttling somewhere in the path from
the process to the I/O scheduler. So we should mark bfqq remained idle
when expired for two reasons: BFQQE_NO_MORE_REQUESTS or BFQQE_TOO_IDLE.
More details can be found in comment of
bfq_bfqq_update_budg_for_activation.
So we should mark bfqq remained idle expired for BFQQE_NO_MORE_REQUESTS
or BFQQE_TOO_IDLE instead of (reason != BFQQE_BUDGET_TIMEOUT &&
reason != BFQQE_BUDGET_EXHAUSTED).

Signed-off-by: Kemeng Shi <shikemeng@...weicloud.com>
---
 block/bfq-iosched.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/block/bfq-iosched.c b/block/bfq-iosched.c
index 777dcab73c8e..3f5c740664ce 100644
--- a/block/bfq-iosched.c
+++ b/block/bfq-iosched.c
@@ -4420,8 +4420,8 @@ void bfq_bfqq_expire(struct bfq_data *bfqd,

 	/* mark bfqq as waiting a request only if a bic still points to it */
 	if (!bfq_bfqq_busy(bfqq) &&
-	    reason != BFQQE_BUDGET_TIMEOUT &&
-	    reason != BFQQE_BUDGET_EXHAUSTED) {
+	    reason == BFQQE_NO_MORE_REQUESTS &&
+	    reason == BFQQE_TOO_IDLE) {
 		bfq_mark_bfqq_non_blocking_wait_rq(bfqq);
 		/*
 		 * Not setting service to 0, because, if the next rq
-- 
2.30.0