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From: Bart Van Assche <bvanassche@acm.org>
To: Bean Huo <huobean@gmail.com>, Can Guo <cang@codeaurora.org>,
	asutoshd@codeaurora.org, nguyenb@codeaurora.org,
	hongwus@codeaurora.org, linux-scsi@vger.kernel.org,
	kernel-team@android.com
Cc: Stanley Chu <stanley.chu@mediatek.com>,
	Alim Akhtar <alim.akhtar@samsung.com>,
	Avri Altman <avri.altman@wdc.com>,
	"James E.J. Bottomley" <jejb@linux.ibm.com>,
	"Martin K. Petersen" <martin.petersen@oracle.com>,
	Matthias Brugger <matthias.bgg@gmail.com>,
	Bean Huo <beanhuo@micron.com>, Jaegeuk Kim <jaegeuk@kernel.org>,
	Adrian Hunter <adrian.hunter@intel.com>,
	Kiwoong Kim <kwmad.kim@samsung.com>,
	Satya Tangirala <satyat@google.com>,
	open list <linux-kernel@vger.kernel.org>,
	"moderated list:ARM/Mediatek SoC support"
	<linux-arm-kernel@lists.infradead.org>,
	"moderated list:ARM/Mediatek SoC support"
	<linux-mediatek@lists.infradead.org>
Subject: Re: [PATCH v1 2/3] scsi: ufs: Optimize host lock on transfer requests send/compl paths
Date: Wed, 2 Jun 2021 17:18:51 -0700	[thread overview]
Message-ID: <200da9c5-ea20-819e-2b11-7f45e8b05cbb@acm.org> (raw)
In-Reply-To: <6d6d296a84f1e62f65fda4d172a85bb35d9a3684.camel@gmail.com>

On 5/31/21 9:04 AM, Bean Huo wrote:
> I did a UFS queue limitation test before, observed that once the
> queue is full, then the active task number in the queue will get
> down. For the Nvme, the scenario is the same. You can refer to the
> slide 23, and slide 24 in the pdf: 
> https://elinux.org/images/6/6c/Linux_Storage_System_Bottleneck_Exploration_V0.3.pdf
> I don't know if your patch can fix this issue.

Hi Bean,

That's a very interesting presentation. Unfortunately the overhead for
SCSI in that presentation includes the SCSI core + UFS driver. Given the
use of the host lock in the version of the UFS driver that was used to
prepare that presentation, the overhead introduced by the UFS driver may
be significant. Maybe someone should measure the overhead of the
scsi_debug driver and compare it with the NVMe loopback driver to get a
better idea of how the overhead of these two subsystems compare to each
other?

Bart.

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  reply	other threads:[~2021-06-03  0:22 UTC|newest]

Thread overview: 14+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
     [not found] <1621845419-14194-1-git-send-email-cang@codeaurora.org>
2021-05-24  8:36 ` [PATCH v1 2/3] scsi: ufs: Optimize host lock on transfer requests send/compl paths Can Guo
2021-05-24 20:10   ` Bart Van Assche
     [not found]     ` <d4ff8e1a-f368-6720-798a-a2a31a4d41fb@codeaurora.org>
2021-05-25  8:24       ` Avri Altman
2021-05-28  7:30         ` Avri Altman
     [not found]     ` <0cfbf580e340073ff972be493a59dbe7@codeaurora.org>
2021-05-25 16:40       ` Bart Van Assche
2021-05-31 16:04   ` Bean Huo
2021-06-03  0:18     ` Bart Van Assche [this message]
2021-06-03  2:54   ` Stanley Chu
2021-06-17  2:49   ` Bart Van Assche
2021-06-28 22:58   ` Bart Van Assche
     [not found]     ` <464097469b09752ce4ebb38c08f1a94a@codeaurora.org>
2021-07-01 15:57       ` Bart Van Assche
2021-05-24  8:36 ` [PATCH v1 3/3] scsi: ufs: Utilize Transfer Request List Completion Notification Register Can Guo
2021-05-31 16:05   ` Bean Huo
2021-06-03  2:54   ` Stanley Chu

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