linux-kernel - [PATCH 2/2] ufs: don't use the fair tag sharings

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Date:   Tue, 9 May 2023 14:52:30 +0800
From:   Ed Tsai <ed.tsai@...iatek.com>
To:     <axboe@...nel.dk>
CC:     <linux-block@...r.kernel.org>, <linux-scsi@...r.kernel.org>,
        <linux-kernel@...r.kernel.org>, <martin.petersen@...cle.com>,
        <bvanassche@....org>, <stanley.chu@...iatek.com>,
        <peter.wang@...iatek.com>, <chun-hung.wu@...iatek.com>,
        <alice.chao@...iatek.com>, <powen.kao@...iatek.com>,
        <naomi.chu@...iatek.com>, <wsd_upstream@...iatek.com>,
        Ed Tsai <ed.tsai@...iatek.com>
Subject: [PATCH 2/2] ufs: don't use the fair tag sharings

The tags allocation is limited by the fair sharing algorithm. It hurts
the performance for UFS devices, because the queue depth of general I/O
is reduced by half once the UFS send a control command.

Signed-off-by: Ed Tsai <ed.tsai@...iatek.com>
---
 drivers/ufs/core/ufshcd.c | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/drivers/ufs/core/ufshcd.c b/drivers/ufs/core/ufshcd.c
index 17d7bb875fee..e96a50265285 100644
--- a/drivers/ufs/core/ufshcd.c
+++ b/drivers/ufs/core/ufshcd.c
@@ -5149,6 +5149,9 @@ static int ufshcd_slave_configure(struct scsi_device *sdev)
 	blk_queue_update_dma_pad(q, PRDT_DATA_BYTE_COUNT_PAD - 1);
 	if (hba->quirks & UFSHCD_QUIRK_4KB_DMA_ALIGNMENT)
 		blk_queue_update_dma_alignment(q, 4096 - 1);
+
+	blk_queue_flag_clear(QUEUE_FLAG_FAIR_TAG_SHARING, q);
+
 	/*
 	 * Block runtime-pm until all consumers are added.
 	 * Refer ufshcd_setup_links().
-- 
2.18.0